1> ## Documentation Index
2> Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt
3> Use this file to discover all available pages before exploring further.
4
5# Extend Claude with skills
6
7> Create, manage, and share skills to extend Claude's capabilities in Claude Code. Includes custom commands and bundled skills.
8
9Skills extend what Claude can do. Create a `SKILL.md` file with instructions, and Claude adds it to its toolkit. Claude uses skills when relevant, or you can invoke one directly with `/skill-name`.
10
11Create a skill when you keep pasting the same instructions, checklist, or multi-step procedure into chat, or when a section of CLAUDE.md has grown into a procedure rather than a fact. Unlike CLAUDE.md content, a skill's body loads only when it's used, so long reference material costs almost nothing until you need it.
12
13<Note>
14 For built-in commands like `/help` and `/compact`, and bundled skills like `/debug` and `/simplify`, see the [commands reference](/en/commands).
15
16 **Custom commands have been merged into skills.** A file at `.claude/commands/deploy.md` and a skill at `.claude/skills/deploy/SKILL.md` both create `/deploy` and work the same way. Your existing `.claude/commands/` files keep working. Skills add optional features: a directory for supporting files, frontmatter to [control whether you or Claude invokes them](#control-who-invokes-a-skill), and the ability for Claude to load them automatically when relevant.
17</Note>
18
19Claude Code skills follow the [Agent Skills](https://agentskills.io) open standard, which works across multiple AI tools. Claude Code extends the standard with additional features like [invocation control](#control-who-invokes-a-skill), [subagent execution](#run-skills-in-a-subagent), and [dynamic context injection](#inject-dynamic-context).
20
21## Bundled skills
22
23Claude Code includes a set of bundled skills that are available in every session, including `/simplify`, `/batch`, `/debug`, `/loop`, and `/claude-api`. Unlike most built-in commands, which execute fixed logic directly, bundled skills are prompt-based: they give Claude detailed instructions and let it orchestrate the work using its tools. You invoke them the same way as any other skill, by typing `/` followed by the skill name.
24
25Bundled skills are listed alongside built-in commands in the [commands reference](/en/commands), marked **Skill** in the Purpose column.
26
27## Getting started
28
29### Create your first skill
30
31This example creates a skill that summarizes the uncommitted changes in your git repository and flags anything risky. It pulls the live diff into the prompt before Claude reads it, so the response is grounded in your actual working tree rather than what Claude can guess from open files. Claude loads the skill automatically when you ask about your changes, or you can invoke it directly with `/summarize-changes`.
32
33<Steps>
34 <Step title="Create the skill directory">
35 Create a directory for the skill in your personal skills folder. Personal skills are available across all your projects.
36
37 ```bash theme={null}
38 mkdir -p ~/.claude/skills/summarize-changes
39 ```
40 </Step>
41
42 <Step title="Write SKILL.md">
43 Every skill needs a `SKILL.md` file with two parts: YAML frontmatter between `---` markers that tells Claude when to use the skill, and markdown content with the instructions Claude follows when the skill runs. The directory name becomes the command you type, and the `description` helps Claude decide when to load the skill automatically.
44
45 Save this to `~/.claude/skills/summarize-changes/SKILL.md`:
46
47 ```yaml theme={null}
48 ---
49 description: Summarizes uncommitted changes and flags anything risky. Use when the user asks what changed, wants a commit message, or asks to review their diff.
50 ---
51
52 ## Current changes
53
54 !`git diff HEAD`
55
56 ## Instructions
57
58 Summarize the changes above in two or three bullet points, then list any risks you notice such as missing error handling, hardcoded values, or tests that need updating. If the diff is empty, say there are no uncommitted changes.
59 ```
60
61 The `` !`git diff HEAD` `` line uses [dynamic context injection](#inject-dynamic-context): Claude Code runs the command and replaces the line with its output before Claude sees the skill content, so the instructions arrive with the current diff already inlined.
62 </Step>
63
64 <Step title="Test the skill">
65 Open a git project, make a small edit to any file, and start Claude Code by running `claude`. You can test the skill two ways.
66
67 **Let Claude invoke it automatically** by asking something that matches the description:
68
69 ```text theme={null}
70 What did I change?
71 ```
72
73 **Or invoke it directly** with the skill name:
74
75 ```text theme={null}
76 /summarize-changes
77 ```
78
79 Either way, Claude should respond with a short summary of your edit and a list of risks.
80 </Step>
81</Steps>
82
83### Where skills live
84
85Where you store a skill determines who can use it:
86
87| Location | Path | Applies to |
88| :--------- | :-------------------------------------------------- | :----------------------------- |
89| Enterprise | See [managed settings](/en/settings#settings-files) | All users in your organization |
90| Personal | `~/.claude/skills/<skill-name>/SKILL.md` | All your projects |
91| Project | `.claude/skills/<skill-name>/SKILL.md` | This project only |
92| Plugin | `<plugin>/skills/<skill-name>/SKILL.md` | Where plugin is enabled |
93
94When skills share the same name across levels, enterprise overrides personal, and personal overrides project. Plugin skills use a `plugin-name:skill-name` namespace, so they cannot conflict with other levels. If you have files in `.claude/commands/`, those work the same way, but if a skill and a command share the same name, the skill takes precedence.
95
96#### Live change detection
97
98Claude Code watches skill directories for file changes. Adding, editing, or removing a skill under `~/.claude/skills/`, the project `.claude/skills/`, or a `.claude/skills/` inside an `--add-dir` directory takes effect within the current session without restarting. Creating a top-level skills directory that did not exist when the session started requires restarting Claude Code so the new directory can be watched.
99
100#### Automatic discovery from parent and nested directories
101
102Project skills load from `.claude/skills/` in your starting directory and in every parent directory up to the repository root, so starting Claude in a subdirectory still picks up skills defined at the root. When you work with files in subdirectories below your starting directory, Claude Code also discovers skills from nested `.claude/skills/` directories on demand. For example, if you're editing a file in `packages/frontend/`, Claude Code also looks for skills in `packages/frontend/.claude/skills/`. This supports monorepo setups where packages have their own skills.
103
104Each skill is a directory with `SKILL.md` as the entrypoint:
105
106```text theme={null}
107my-skill/
108├── SKILL.md # Main instructions (required)
109├── template.md # Template for Claude to fill in
110├── examples/
111│ └── sample.md # Example output showing expected format
112└── scripts/
113 └── validate.sh # Script Claude can execute
114```
115
116The `SKILL.md` contains the main instructions and is required. Other files are optional and let you build more powerful skills: templates for Claude to fill in, example outputs showing the expected format, scripts Claude can execute, or detailed reference documentation. Reference these files from your `SKILL.md` so Claude knows what they contain and when to load them. See [Add supporting files](#add-supporting-files) for more details.
117
118<Note>
119 Files in `.claude/commands/` still work and support the same [frontmatter](#frontmatter-reference). Skills are recommended since they support additional features like supporting files.
120</Note>
121
122#### Skills from additional directories
123
124The `--add-dir` flag [grants file access](/en/permissions#additional-directories-grant-file-access-not-configuration) rather than configuration discovery, but skills are an exception: `.claude/skills/` within an added directory is loaded automatically. See [Live change detection](#live-change-detection) for how edits are picked up during a session.
125
126Other `.claude/` configuration such as subagents, commands, and output styles is not loaded from additional directories. See the [exceptions table](/en/permissions#additional-directories-grant-file-access-not-configuration) for the complete list of what is and isn't loaded, and the recommended ways to share configuration across projects.
127
128<Note>
129 CLAUDE.md files from `--add-dir` directories are not loaded by default. To load them, set `CLAUDE_CODE_ADDITIONAL_DIRECTORIES_CLAUDE_MD=1`. See [Load from additional directories](/en/memory#load-from-additional-directories).
130</Note>
131
132## Configure skills
133
134Skills are configured through YAML frontmatter at the top of `SKILL.md` and the markdown content that follows.
135
136### Types of skill content
137
138Skill files can contain any instructions, but thinking about how you want to invoke them helps guide what to include:
139
140**Reference content** adds knowledge Claude applies to your current work. Conventions, patterns, style guides, domain knowledge. This content runs inline so Claude can use it alongside your conversation context.
141
142```yaml theme={null}
143---
144name: api-conventions
145description: API design patterns for this codebase
146---
147
148When writing API endpoints:
149- Use RESTful naming conventions
150- Return consistent error formats
151- Include request validation
152```
153
154**Task content** gives Claude step-by-step instructions for a specific action, like deployments, commits, or code generation. These are often actions you want to invoke directly with `/skill-name` rather than letting Claude decide when to run them. Add `disable-model-invocation: true` to prevent Claude from triggering it automatically.
155
156```yaml theme={null}
157---
158name: deploy
159description: Deploy the application to production
160context: fork
161disable-model-invocation: true
162---
163
164Deploy the application:
1651. Run the test suite
1662. Build the application
1673. Push to the deployment target
168```
169
170Your `SKILL.md` can contain anything, but thinking through how you want the skill invoked (by you, by Claude, or both) and where you want it to run (inline or in a subagent) helps guide what to include. For complex skills, you can also [add supporting files](#add-supporting-files) to keep the main skill focused.
171
172Keep the body itself concise. Once a skill loads, its content [stays in context across turns](#skill-content-lifecycle), so every line is a recurring token cost. State what to do rather than narrating how or why, and apply the same conciseness test you would for [CLAUDE.md content](/en/best-practices#write-an-effective-claude-md).
173
174### Frontmatter reference
175
176Beyond the markdown content, you can configure skill behavior using YAML frontmatter fields between `---` markers at the top of your `SKILL.md` file:
177
178```yaml theme={null}
179---
180name: my-skill
181description: What this skill does
182disable-model-invocation: true
183allowed-tools: Read Grep
184---
185
186Your skill instructions here...
187```
188
189All fields are optional. Only `description` is recommended so Claude knows when to use the skill.
190
191| Field | Required | Description |
192| :------------------------- | :---------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
193| `name` | No | Display name for the skill. If omitted, uses the directory name. Lowercase letters, numbers, and hyphens only (max 64 characters). |
194| `description` | Recommended | What the skill does and when to use it. Claude uses this to decide when to apply the skill. If omitted, uses the first paragraph of markdown content. Put the key use case first: the combined `description` and `when_to_use` text is truncated at 1,536 characters in the skill listing to reduce context usage. |
195| `when_to_use` | No | Additional context for when Claude should invoke the skill, such as trigger phrases or example requests. Appended to `description` in the skill listing and counts toward the 1,536-character cap. |
196| `argument-hint` | No | Hint shown during autocomplete to indicate expected arguments. Example: `[issue-number]` or `[filename] [format]`. |
197| `arguments` | No | Named positional arguments for [`$name` substitution](#available-string-substitutions) in the skill content. Accepts a space-separated string or a YAML list. Names map to argument positions in order. |
198| `disable-model-invocation` | No | Set to `true` to prevent Claude from automatically loading this skill. Use for workflows you want to trigger manually with `/name`. Also prevents the skill from being [preloaded into subagents](/en/sub-agents#preload-skills-into-subagents). Default: `false`. |
199| `user-invocable` | No | Set to `false` to hide from the `/` menu. Use for background knowledge users shouldn't invoke directly. Default: `true`. |
200| `allowed-tools` | No | Tools Claude can use without asking permission when this skill is active. Accepts a space-separated string or a YAML list. |
201| `model` | No | Model to use when this skill is active. The override applies for the rest of the current turn and is not saved to settings; the session model resumes on your next prompt. Accepts the same values as [`/model`](/en/model-config), or `inherit` to keep the active model. |
202| `effort` | No | [Effort level](/en/model-config#adjust-effort-level) when this skill is active. Overrides the session effort level. Default: inherits from session. Options: `low`, `medium`, `high`, `xhigh`, `max`; available levels depend on the model. |
203| `context` | No | Set to `fork` to run in a forked subagent context. |
204| `agent` | No | Which subagent type to use when `context: fork` is set. |
205| `hooks` | No | Hooks scoped to this skill's lifecycle. See [Hooks in skills and agents](/en/hooks#hooks-in-skills-and-agents) for configuration format. |
206| `paths` | No | Glob patterns that limit when this skill is activated. Accepts a comma-separated string or a YAML list. When set, Claude loads the skill automatically only when working with files matching the patterns. Uses the same format as [path-specific rules](/en/memory#path-specific-rules). |
207| `shell` | No | Shell to use for `` !`command` `` and ` ```! ` blocks in this skill. Accepts `bash` (default) or `powershell`. Setting `powershell` runs inline shell commands via PowerShell on Windows. Requires `CLAUDE_CODE_USE_POWERSHELL_TOOL=1`. |
208
209#### Available string substitutions
210
211Skills support string substitution for dynamic values in the skill content:
212
213| Variable | Description |
214| :--------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
215| `$ARGUMENTS` | All arguments passed when invoking the skill. If `$ARGUMENTS` is not present in the content, arguments are appended as `ARGUMENTS: <value>`. |
216| `$ARGUMENTS[N]` | Access a specific argument by 0-based index, such as `$ARGUMENTS[0]` for the first argument. |
217| `$N` | Shorthand for `$ARGUMENTS[N]`, such as `$0` for the first argument or `$1` for the second. |
218| `$name` | Named argument declared in the [`arguments`](#frontmatter-reference) frontmatter list. Names map to positions in order, so with `arguments: [issue, branch]` the placeholder `$issue` expands to the first argument and `$branch` to the second. |
219| `${CLAUDE_SESSION_ID}` | The current session ID. Useful for logging, creating session-specific files, or correlating skill output with sessions. |
220| `${CLAUDE_EFFORT}` | The current effort level: `low`, `medium`, `high`, `xhigh`, or `max`. Use this to adapt skill instructions to the active effort setting. |
221| `${CLAUDE_SKILL_DIR}` | The directory containing the skill's `SKILL.md` file. For plugin skills, this is the skill's subdirectory within the plugin, not the plugin root. Use this in bash injection commands to reference scripts or files bundled with the skill, regardless of the current working directory. |
222
223Indexed arguments use shell-style quoting, so wrap multi-word values in quotes to pass them as a single argument. For example, `/my-skill "hello world" second` makes `$0` expand to `hello world` and `$1` to `second`. The `$ARGUMENTS` placeholder always expands to the full argument string as typed.
224
225**Example using substitutions:**
226
227```yaml theme={null}
228---
229name: session-logger
230description: Log activity for this session
231---
232
233Log the following to logs/${CLAUDE_SESSION_ID}.log:
234
235$ARGUMENTS
236```
237
238### Add supporting files
239
240Skills can include multiple files in their directory. This keeps `SKILL.md` focused on the essentials while letting Claude access detailed reference material only when needed. Large reference docs, API specifications, or example collections don't need to load into context every time the skill runs.
241
242```text theme={null}
243my-skill/
244├── SKILL.md (required - overview and navigation)
245├── reference.md (detailed API docs - loaded when needed)
246├── examples.md (usage examples - loaded when needed)
247└── scripts/
248 └── helper.py (utility script - executed, not loaded)
249```
250
251Reference supporting files from `SKILL.md` so Claude knows what each file contains and when to load it:
252
253```markdown theme={null}
254## Additional resources
255
256- For complete API details, see [reference.md](reference.md)
257- For usage examples, see [examples.md](examples.md)
258```
259
260<Tip>Keep `SKILL.md` under 500 lines. Move detailed reference material to separate files.</Tip>
261
262### Control who invokes a skill
263
264By default, both you and Claude can invoke any skill. You can type `/skill-name` to invoke it directly, and Claude can load it automatically when relevant to your conversation. Two frontmatter fields let you restrict this:
265
266* **`disable-model-invocation: true`**: Only you can invoke the skill. Use this for workflows with side effects or that you want to control timing, like `/commit`, `/deploy`, or `/send-slack-message`. You don't want Claude deciding to deploy because your code looks ready.
267
268* **`user-invocable: false`**: Only Claude can invoke the skill. Use this for background knowledge that isn't actionable as a command. A `legacy-system-context` skill explains how an old system works. Claude should know this when relevant, but `/legacy-system-context` isn't a meaningful action for users to take.
269
270This example creates a deploy skill that only you can trigger. The `disable-model-invocation: true` field prevents Claude from running it automatically:
271
272```yaml theme={null}
273---
274name: deploy
275description: Deploy the application to production
276disable-model-invocation: true
277---
278
279Deploy $ARGUMENTS to production:
280
2811. Run the test suite
2822. Build the application
2833. Push to the deployment target
2844. Verify the deployment succeeded
285```
286
287Here's how the two fields affect invocation and context loading:
288
289| Frontmatter | You can invoke | Claude can invoke | When loaded into context |
290| :------------------------------- | :------------- | :---------------- | :----------------------------------------------------------- |
291| (default) | Yes | Yes | Description always in context, full skill loads when invoked |
292| `disable-model-invocation: true` | Yes | No | Description not in context, full skill loads when you invoke |
293| `user-invocable: false` | No | Yes | Description always in context, full skill loads when invoked |
294
295<Note>
296 In a regular session, skill descriptions are loaded into context so Claude knows what's available, but full skill content only loads when invoked. [Subagents with preloaded skills](/en/sub-agents#preload-skills-into-subagents) work differently: the full skill content is injected at startup.
297</Note>
298
299### Skill content lifecycle
300
301When you or Claude invoke a skill, the rendered `SKILL.md` content enters the conversation as a single message and stays there for the rest of the session. Claude Code does not re-read the skill file on later turns, so write guidance that should apply throughout a task as standing instructions rather than one-time steps.
302
303[Auto-compaction](/en/how-claude-code-works#when-context-fills-up) carries invoked skills forward within a token budget. When the conversation is summarized to free context, Claude Code re-attaches the most recent invocation of each skill after the summary, keeping the first 5,000 tokens of each. Re-attached skills share a combined budget of 25,000 tokens. Claude Code fills this budget starting from the most recently invoked skill, so older skills can be dropped entirely after compaction if you have invoked many in one session.
304
305If a skill seems to stop influencing behavior after the first response, the content is usually still present and the model is choosing other tools or approaches. Strengthen the skill's `description` and instructions so the model keeps preferring it, or use [hooks](/en/hooks) to enforce behavior deterministically. If the skill is large or you invoked several others after it, re-invoke it after compaction to restore the full content.
306
307### Pre-approve tools for a skill
308
309The `allowed-tools` field grants permission for the listed tools while the skill is active, so Claude can use them without prompting you for approval. It does not restrict which tools are available: every tool remains callable, and your [permission settings](/en/permissions) still govern tools that are not listed.
310
311For skills checked into a project's `.claude/skills/` directory, `allowed-tools` takes effect after you accept the workspace trust dialog for that folder, the same as permission rules in `.claude/settings.json`. Review project skills before trusting a repository, since a skill can grant itself broad tool access.
312
313This skill lets Claude run git commands without per-use approval whenever you invoke it:
314
315```yaml theme={null}
316---
317name: commit
318description: Stage and commit the current changes
319disable-model-invocation: true
320allowed-tools: Bash(git add *) Bash(git commit *) Bash(git status *)
321---
322```
323
324To block a skill from using certain tools, add deny rules in your [permission settings](/en/permissions) instead.
325
326### Pass arguments to skills
327
328Both you and Claude can pass arguments when invoking a skill. Arguments are available via the `$ARGUMENTS` placeholder.
329
330This skill fixes a GitHub issue by number. The `$ARGUMENTS` placeholder gets replaced with whatever follows the skill name:
331
332```yaml theme={null}
333---
334name: fix-issue
335description: Fix a GitHub issue
336disable-model-invocation: true
337---
338
339Fix GitHub issue $ARGUMENTS following our coding standards.
340
3411. Read the issue description
3422. Understand the requirements
3433. Implement the fix
3444. Write tests
3455. Create a commit
346```
347
348When you run `/fix-issue 123`, Claude receives "Fix GitHub issue 123 following our coding standards..."
349
350If you invoke a skill with arguments but the skill doesn't include `$ARGUMENTS`, Claude Code appends `ARGUMENTS: <your input>` to the end of the skill content so Claude still sees what you typed.
351
352To access individual arguments by position, use `$ARGUMENTS[N]` or the shorter `$N`:
353
354```yaml theme={null}
355---
356name: migrate-component
357description: Migrate a component from one framework to another
358---
359
360Migrate the $ARGUMENTS[0] component from $ARGUMENTS[1] to $ARGUMENTS[2].
361Preserve all existing behavior and tests.
362```
363
364Running `/migrate-component SearchBar React Vue` replaces `$ARGUMENTS[0]` with `SearchBar`, `$ARGUMENTS[1]` with `React`, and `$ARGUMENTS[2]` with `Vue`. The same skill using the `$N` shorthand:
365
366```yaml theme={null}
367---
368name: migrate-component
369description: Migrate a component from one framework to another
370---
371
372Migrate the $0 component from $1 to $2.
373Preserve all existing behavior and tests.
374```
375
376## Advanced patterns
377
378### Inject dynamic context
379
380The `` !`<command>` `` syntax runs shell commands before the skill content is sent to Claude. The command output replaces the placeholder, so Claude receives actual data, not the command itself.
381
382This skill summarizes a pull request by fetching live PR data with the GitHub CLI. The `` !`gh pr diff` `` and other commands run first, and their output gets inserted into the prompt:
383
384```yaml theme={null}
385---
386name: pr-summary
387description: Summarize changes in a pull request
388context: fork
389agent: Explore
390allowed-tools: Bash(gh *)
391---
392
393## Pull request context
394- PR diff: !`gh pr diff`
395- PR comments: !`gh pr view --comments`
396- Changed files: !`gh pr diff --name-only`
397
398## Your task
399Summarize this pull request...
400```
401
402When this skill runs:
403
4041. Each `` !`<command>` `` executes immediately (before Claude sees anything)
4052. The output replaces the placeholder in the skill content
4063. Claude receives the fully-rendered prompt with actual PR data
407
408This is preprocessing, not something Claude executes. Claude only sees the final result.
409
410Substitution runs once over the original file. Command output is inserted as plain text and is not re-scanned for further `` !`<command>` `` placeholders, so a command cannot emit a placeholder for a later pass to expand.
411
412For multi-line commands, use a fenced code block opened with ` ```! ` instead of the inline form:
413
414````markdown theme={null}
415## Environment
416```!
417node --version
418npm --version
419git status --short
420```
421````
422
423To disable this behavior for skills and custom commands from user, project, plugin, or [additional-directory](#skills-from-additional-directories) sources, set `"disableSkillShellExecution": true` in [settings](/en/settings). Each command is replaced with `[shell command execution disabled by policy]` instead of being run. Bundled and managed skills are not affected. This setting is most useful in [managed settings](/en/permissions#managed-settings), where users cannot override it.
424
425<Tip>
426 To request deeper reasoning when a skill runs, include `ultrathink` anywhere in the skill content. See [Use ultrathink for one-off deep reasoning](/en/model-config#use-ultrathink-for-one-off-deep-reasoning).
427</Tip>
428
429### Run skills in a subagent
430
431Add `context: fork` to your frontmatter when you want a skill to run in isolation. The skill content becomes the prompt that drives the subagent. It won't have access to your conversation history.
432
433<Warning>
434 `context: fork` only makes sense for skills with explicit instructions. If your skill contains guidelines like "use these API conventions" without a task, the subagent receives the guidelines but no actionable prompt, and returns without meaningful output.
435</Warning>
436
437Skills and [subagents](/en/sub-agents) work together in two directions:
438
439| Approach | System prompt | Task | Also loads |
440| :--------------------------- | :----------------------- | :-------------------------- | :-------------------------------------------------- |
441| Skill with `context: fork` | From agent type | SKILL.md content | CLAUDE.md, except when the agent is Explore or Plan |
442| Subagent with `skills` field | Subagent's markdown body | Claude's delegation message | Preloaded skills + CLAUDE.md |
443
444With `context: fork`, you write the task in your skill and pick an agent type to execute it. The built-in Explore and Plan agents [skip CLAUDE.md and git status](/en/sub-agents#what-loads-at-startup) to keep their context small, so a forked skill using `agent: Explore` sees only the SKILL.md content and the agent's own system prompt. For the inverse, where you define a custom subagent that uses skills as reference material, see [Subagents](/en/sub-agents#preload-skills-into-subagents).
445
446#### Example: Research skill using Explore agent
447
448This skill runs research in a forked Explore agent. The skill content becomes the task, and the agent provides read-only tools optimized for codebase exploration:
449
450```yaml theme={null}
451---
452name: deep-research
453description: Research a topic thoroughly
454context: fork
455agent: Explore
456---
457
458Research $ARGUMENTS thoroughly:
459
4601. Find relevant files using Glob and Grep
4612. Read and analyze the code
4623. Summarize findings with specific file references
463```
464
465When this skill runs:
466
4671. A new isolated context is created
4682. The subagent receives the skill content as its prompt ("Research \$ARGUMENTS thoroughly...")
4693. The `agent` field determines the execution environment (model, tools, and permissions)
4704. Results are summarized and returned to your main conversation
471
472The `agent` field specifies which subagent configuration to use. Options include built-in agents (`Explore`, `Plan`, `general-purpose`) or any custom subagent from `.claude/agents/`. If omitted, uses `general-purpose`.
473
474### Restrict Claude's skill access
475
476By default, Claude can invoke any skill that doesn't have `disable-model-invocation: true` set. Skills that define `allowed-tools` grant Claude access to those tools without per-use approval when the skill is active. Your [permission settings](/en/permissions) still govern baseline approval behavior for all other tools. A few built-in commands are also available through the Skill tool, including `/init`, `/review`, and `/security-review`. Other built-in commands such as `/compact` are not.
477
478Three ways to control which skills Claude can invoke:
479
480**Disable all skills** by denying the Skill tool in `/permissions`:
481
482```text theme={null}
483# Add to deny rules:
484Skill
485```
486
487**Allow or deny specific skills** using [permission rules](/en/permissions):
488
489```text theme={null}
490# Allow only specific skills
491Skill(commit)
492Skill(review-pr *)
493
494# Deny specific skills
495Skill(deploy *)
496```
497
498Permission syntax: `Skill(name)` for exact match, `Skill(name *)` for prefix match with any arguments.
499
500**Hide individual skills** by adding `disable-model-invocation: true` to their frontmatter. This removes the skill from Claude's context entirely.
501
502<Note>
503 The `user-invocable` field only controls menu visibility, not Skill tool access. Use `disable-model-invocation: true` to block programmatic invocation.
504</Note>
505
506### Override skill visibility from settings
507
508The `skillOverrides` setting controls skill visibility from your [settings](/en/settings) instead of the skill's own frontmatter. Use it for skills whose SKILL.md you don't want to edit, such as ones checked into a shared project repo or provided by an MCP server. The `/skills` menu writes it for you: highlight a skill and press `Space` to cycle states, then `Enter` to save to `.claude/settings.local.json`.
509
510Each key is a skill name and each value is one of four states:
511
512| Value | Listed to Claude | In `/` menu |
513| :---------------------- | :------------------- | :---------- |
514| `"on"` | Name and description | Yes |
515| `"name-only"` | Name only | Yes |
516| `"user-invocable-only"` | Hidden | Yes |
517| `"off"` | Hidden | Hidden |
518
519A skill that is absent from `skillOverrides` is treated as `"on"`. The example below collapses one skill to its name and turns another off entirely:
520
521```json theme={null}
522{
523 "skillOverrides": {
524 "legacy-context": "name-only",
525 "deploy": "off"
526 }
527}
528```
529
530Plugin skills are not affected by `skillOverrides`. Manage those through `/plugin` instead.
531
532## Share skills
533
534Skills can be distributed at different scopes depending on your audience:
535
536* **Project skills**: Commit `.claude/skills/` to version control
537* **Plugins**: Create a `skills/` directory in your [plugin](/en/plugins)
538* **Managed**: Deploy organization-wide through [managed settings](/en/settings#settings-files)
539
540### Generate visual output
541
542Skills can bundle and run scripts in any language, giving Claude capabilities beyond what's possible in a single prompt. One powerful pattern is generating visual output: interactive HTML files that open in your browser for exploring data, debugging, or creating reports.
543
544This example creates a codebase explorer: an interactive tree view where you can expand and collapse directories, see file sizes at a glance, and identify file types by color.
545
546Create the Skill directory:
547
548```bash theme={null}
549mkdir -p ~/.claude/skills/codebase-visualizer/scripts
550```
551
552Save this to `~/.claude/skills/codebase-visualizer/SKILL.md`. The description tells Claude when to activate this Skill, and the instructions tell Claude to run the bundled script. The script path uses [`${CLAUDE_SKILL_DIR}`](#available-string-substitutions) so it resolves correctly whether the skill is installed at the personal, project, or plugin level:
553
554````yaml theme={null}
555---
556name: codebase-visualizer
557description: Generate an interactive collapsible tree visualization of your codebase. Use when exploring a new repo, understanding project structure, or identifying large files.
558allowed-tools: Bash(python3 *)
559---
560
561# Codebase Visualizer
562
563Generate an interactive HTML tree view that shows your project's file structure with collapsible directories.
564
565## Usage
566
567Run the visualization script from your project root:
568
569```bash
570python3 ${CLAUDE_SKILL_DIR}/scripts/visualize.py .
571```
572
573This creates `codebase-map.html` in the current directory and opens it in your default browser.
574
575## What the visualization shows
576
577- **Collapsible directories**: Click folders to expand/collapse
578- **File sizes**: Displayed next to each file
579- **Colors**: Different colors for different file types
580- **Directory totals**: Shows aggregate size of each folder
581````
582
583Save this to `~/.claude/skills/codebase-visualizer/scripts/visualize.py`. This script scans a directory tree and generates a self-contained HTML file with:
584
585* A **summary sidebar** showing file count, directory count, total size, and number of file types
586* A **bar chart** breaking down the codebase by file type (top 8 by size)
587* A **collapsible tree** where you can expand and collapse directories, with color-coded file type indicators
588
589The script requires Python 3 but uses only built-in libraries, so there are no packages to install:
590
591```python expandable theme={null}
592#!/usr/bin/env python3
593"""Generate an interactive collapsible tree visualization of a codebase."""
594
595import json
596import sys
597import webbrowser
598from html import escape
599from pathlib import Path
600from collections import Counter
601
602IGNORE = {'.git', 'node_modules', '__pycache__', '.venv', 'venv', 'dist', 'build'}
603
604def scan(path: Path, stats: dict) -> dict:
605 result = {"name": path.name, "children": [], "size": 0}
606 try:
607 for item in sorted(path.iterdir()):
608 if item.name in IGNORE or item.name.startswith('.'):
609 continue
610 if item.is_file():
611 size = item.stat().st_size
612 ext = item.suffix.lower() or '(no ext)'
613 result["children"].append({"name": item.name, "size": size, "ext": ext})
614 result["size"] += size
615 stats["files"] += 1
616 stats["extensions"][ext] += 1
617 stats["ext_sizes"][ext] += size
618 elif item.is_dir():
619 stats["dirs"] += 1
620 child = scan(item, stats)
621 if child["children"]:
622 result["children"].append(child)
623 result["size"] += child["size"]
624 except PermissionError:
625 pass
626 return result
627
628def generate_html(data: dict, stats: dict, output: Path) -> None:
629 ext_sizes = stats["ext_sizes"]
630 total_size = sum(ext_sizes.values()) or 1
631 sorted_exts = sorted(ext_sizes.items(), key=lambda x: -x[1])[:8]
632 colors = {
633 '.js': '#f7df1e', '.ts': '#3178c6', '.py': '#3776ab', '.go': '#00add8',
634 '.rs': '#dea584', '.rb': '#cc342d', '.css': '#264de4', '.html': '#e34c26',
635 '.json': '#6b7280', '.md': '#083fa1', '.yaml': '#cb171e', '.yml': '#cb171e',
636 '.mdx': '#083fa1', '.tsx': '#3178c6', '.jsx': '#61dafb', '.sh': '#4eaa25',
637 }
638 lang_bars = "".join(
639 f'<div class="bar-row"><span class="bar-label">{ext}</span>'
640 f'<div class="bar" style="width:{(size/total_size)*100}%;background:{colors.get(ext,"#6b7280")}"></div>'
641 f'<span class="bar-pct">{(size/total_size)*100:.1f}%</span></div>'
642 for ext, size in sorted_exts
643 )
644 def fmt(b):
645 if b < 1024: return f"{b} B"
646 if b < 1048576: return f"{b/1024:.1f} KB"
647 return f"{b/1048576:.1f} MB"
648
649 html = f'''<!DOCTYPE html>
650<html><head>
651 <meta charset="utf-8"><title>Codebase Explorer</title>
652 <style>
653 body {{ font: 14px/1.5 system-ui, sans-serif; margin: 0; background: #1a1a2e; color: #eee; }}
654 .container {{ display: flex; height: 100vh; }}
655 .sidebar {{ width: 280px; background: #252542; padding: 20px; border-right: 1px solid #3d3d5c; overflow-y: auto; flex-shrink: 0; }}
656 .main {{ flex: 1; padding: 20px; overflow-y: auto; }}
657 h1 {{ margin: 0 0 10px 0; font-size: 18px; }}
658 h2 {{ margin: 20px 0 10px 0; font-size: 14px; color: #888; text-transform: uppercase; }}
659 .stat {{ display: flex; justify-content: space-between; padding: 8px 0; border-bottom: 1px solid #3d3d5c; }}
660 .stat-value {{ font-weight: bold; }}
661 .bar-row {{ display: flex; align-items: center; margin: 6px 0; }}
662 .bar-label {{ width: 55px; font-size: 12px; color: #aaa; }}
663 .bar {{ height: 18px; border-radius: 3px; }}
664 .bar-pct {{ margin-left: 8px; font-size: 12px; color: #666; }}
665 .tree {{ list-style: none; padding-left: 20px; }}
666 details {{ cursor: pointer; }}
667 summary {{ padding: 4px 8px; border-radius: 4px; }}
668 summary:hover {{ background: #2d2d44; }}
669 .folder {{ color: #ffd700; }}
670 .file {{ display: flex; align-items: center; padding: 4px 8px; border-radius: 4px; }}
671 .file:hover {{ background: #2d2d44; }}
672 .size {{ color: #888; margin-left: auto; font-size: 12px; }}
673 .dot {{ width: 8px; height: 8px; border-radius: 50%; margin-right: 8px; }}
674 </style>
675</head><body>
676 <div class="container">
677 <div class="sidebar">
678 <h1>📊 Summary</h1>
679 <div class="stat"><span>Files</span><span class="stat-value">{stats["files"]:,}</span></div>
680 <div class="stat"><span>Directories</span><span class="stat-value">{stats["dirs"]:,}</span></div>
681 <div class="stat"><span>Total size</span><span class="stat-value">{fmt(data["size"])}</span></div>
682 <div class="stat"><span>File types</span><span class="stat-value">{len(stats["extensions"])}</span></div>
683 <h2>By file type</h2>
684 {lang_bars}
685 </div>
686 <div class="main">
687 <h1>📁 {escape(data["name"])}</h1>
688 <ul class="tree" id="root"></ul>
689 </div>
690 </div>
691 <script>
692 const data = {json.dumps(data)};
693 const colors = {json.dumps(colors)};
694 function fmt(b) {{ if (b < 1024) return b + ' B'; if (b < 1048576) return (b/1024).toFixed(1) + ' KB'; return (b/1048576).toFixed(1) + ' MB'; }}
695 function esc(s) {{ return s.replace(/[&<>"']/g, c => ({{"&":"&","<":"<",">":">",'"':""","'":"'"}}[c])); }}
696 function render(node, parent) {{
697 if (node.children) {{
698 const det = document.createElement('details');
699 det.open = parent === document.getElementById('root');
700 det.innerHTML = `<summary><span class="folder">📁 ${{esc(node.name)}}</span><span class="size">${{fmt(node.size)}}</span></summary>`;
701 const ul = document.createElement('ul'); ul.className = 'tree';
702 node.children.sort((a,b) => (b.children?1:0)-(a.children?1:0) || a.name.localeCompare(b.name));
703 node.children.forEach(c => render(c, ul));
704 det.appendChild(ul);
705 const li = document.createElement('li'); li.appendChild(det); parent.appendChild(li);
706 }} else {{
707 const li = document.createElement('li'); li.className = 'file';
708 li.innerHTML = `<span class="dot" style="background:${{colors[node.ext]||'#6b7280'}}"></span>${{esc(node.name)}}<span class="size">${{fmt(node.size)}}</span>`;
709 parent.appendChild(li);
710 }}
711 }}
712 data.children.forEach(c => render(c, document.getElementById('root')));
713 </script>
714</body></html>'''
715 output.write_text(html)
716
717if __name__ == '__main__':
718 target = Path(sys.argv[1] if len(sys.argv) > 1 else '.').resolve()
719 stats = {"files": 0, "dirs": 0, "extensions": Counter(), "ext_sizes": Counter()}
720 data = scan(target, stats)
721 out = Path('codebase-map.html')
722 generate_html(data, stats, out)
723 print(f'Generated {out.absolute()}')
724 webbrowser.open(f'file://{out.absolute()}')
725```
726
727To test, open Claude Code in any project and ask "Visualize this codebase." Claude runs the script, generates `codebase-map.html`, and opens it in your browser.
728
729This pattern works for any visual output: dependency graphs, test coverage reports, API documentation, or database schema visualizations. The bundled script does the work while Claude handles orchestration.
730
731## Troubleshooting
732
733### Skill not triggering
734
735If Claude doesn't use your skill when expected:
736
7371. Check the description includes keywords users would naturally say
7382. Verify the skill appears in `What skills are available?`
7393. Try rephrasing your request to match the description more closely
7404. Invoke it directly with `/skill-name` if the skill is user-invocable
741
742### Skill triggers too often
743
744If Claude uses your skill when you don't want it:
745
7461. Make the description more specific
7472. Add `disable-model-invocation: true` if you only want manual invocation
748
749### Skill descriptions are cut short
750
751Skill descriptions are loaded into context so Claude knows what's available. All skill names are always included, but if you have many skills, descriptions are shortened to fit the character budget, which can strip the keywords Claude needs to match your request. The budget scales at 1% of the model's context window. When it overflows, descriptions for the skills you invoke least are dropped first, so the skills you actually use keep their full text. Run `/doctor` to see whether the budget is overflowing and which skills are affected.
752
753To raise the budget, set the [`skillListingBudgetFraction`](/en/settings#available-settings) setting (e.g. `0.02` = 2%) or the `SLASH_COMMAND_TOOL_CHAR_BUDGET` environment variable to a fixed character count. To free budget for other skills, set low-priority entries to `"name-only"` in [`skillOverrides`](#override-skill-visibility-from-settings) so they list without a description. You can also trim the `description` and `when_to_use` text at the source: put the key use case first, since each entry's combined text is capped at 1,536 characters regardless of budget. The cap is configurable with [`maxSkillDescriptionChars`](/en/settings#available-settings).
754
755## Related resources
756
757* **[Debug your configuration](/en/debug-your-config)**: diagnose why a skill isn't appearing or triggering
758* **[Subagents](/en/sub-agents)**: delegate tasks to specialized agents
759* **[Plugins](/en/plugins)**: package and distribute skills with other extensions
760* **[Hooks](/en/hooks)**: automate workflows around tool events
761* **[Memory](/en/memory)**: manage CLAUDE.md files for persistent context
762* **[Commands](/en/commands)**: reference for built-in commands and bundled skills
763* **[Permissions](/en/permissions)**: control tool and skill access
