fetching-claude-docs

name: fetching-claude-docs description: "Use PROACTIVELY before writing or modifying any Claude Code component (subagent, skill, hook, rule, slash command, plugin manifest, settings.json, MCP config) to fetch the current official spec from code.claude.com and avoid drifting from up-to-date best practices. Use when user asks 'what is the official spec for X', 'is this the right way to do Y', 'check Anthropic docs for Z'. MUST BE USED at Task 0 of writing-subagents, writing-skills, writing-hooks, writing-rules, writing-claude-md before any design decision."

Fetching Claude Docs

Overview

Fetching Claude docs IS pulling the latest official Anthropic specification before designing or reviewing any Claude Code component.

This skill exists because the project has historically drifted from official docs (e.g. self-invented <law> block removed in v7.1, invalid context: fork on agents fixed in v9.3, inherit anti-pattern formalized only in v10.9.2). Always pull current spec rather than rely on cached memory.

Core principle: Return official source verbatim with URL. Do NOT paraphrase — paraphrasing reintroduces drift.

Violating the letter of the rules is violating the spirit of the rules.

Routing

Pattern: Skill Steps Handoff: none Next: caller skill resumes its Task 1 with fetched spec as input

Task Initialization (MANDATORY)

Before ANY action, create task list using TaskCreate:

TaskCreate for EACH task below:
- Subject: "[fetching-claude-docs] Task N: <action>"
- ActiveForm: "<doing action>"

Tasks:

1. Identify component type and question
2. Resolve URL from mapping table
3. Fetch official spec via WebFetch
4. Return verbatim excerpt + URL to caller

Announce: "Created 4 tasks. Starting execution..."

Task 1: Identify Component Type and Question

Goal: Pin down what to fetch.

Inputs expected from caller:

• component: one of subagent | skill | hook | rule | slash-command | plugin | plugin-marketplace | settings | mcp | output-style | statusline | memory | agent-team | best-practices
• question: specific aspect (e.g. "frontmatter fields", "tool inheritance", "trigger description format")

If caller did not provide: ask user via AskUserQuestion before fetching.

Verification: component is a recognizable Claude Code concept (subagent, skill, hook, etc.) — no static list to match against; llms.txt is the authoritative source in Task 2.

Task 2: Resolve URL from llms.txt

Goal: Pull the official URL index and locate the page for this component. llms.txt is the only source of truth — no static URL table is kept in this skill.

Action:

WebFetch
  url: https://code.claude.com/docs/llms.txt
  prompt: "Return all entries related to: <component>. Include both
           reference and guide URLs if both exist. Quote the URLs verbatim."

Then pick the URL matching the question type:

• spec / fields / schema / frontmatter → reference page (e.g. hooks.md)
• workflow / usage / examples → guide page (e.g. hooks-guide.md)
• both relevant → fetch reference first, guide second in Task 3

Cache: WebFetch has built-in 15-minute cache. The same llms.txt request in the same session is free, so calling this skill multiple times per session has near-zero overhead. Cross-session cost is one ~5KB fetch — negligible.

Why no static URL map: Hard-coded URLs drift (Anthropic restructures docs). llms.txt is small enough that fetching it every time is cheaper than maintaining a stale map.

Verification: Resolved URL ends with .md and is on code.claude.com.

Task 3: Fetch Official Spec

Goal: Pull live content from Anthropic.

Action:

WebFetch
  url: <resolved URL>
  prompt: "Extract the section addressing: <question>. Return verbatim
           excerpts including all rules, frontmatter fields, examples, and
           warnings. Do NOT paraphrase. Include section headers."

Cache: WebFetch has built-in 15-minute cache — repeated calls in the same session are cheap.

On redirect: Follow the redirect URL with a fresh WebFetch.

On failure (non-2xx): Re-fetch https://code.claude.com/docs/llms.txt (bypassing cache if possible) to confirm whether the URL has moved or been removed. Report the change to caller.

Verification: Response contains a section header matching the question topic.

Task 4: Return to Caller

Goal: Hand back structured spec for the caller skill to consume.

Output format (return to caller):

source: <full URL>
fetched_at: <ISO timestamp>
component: <component>
question: <original question>
spec_excerpt: |
  <verbatim official text — preserve markdown formatting>
key_rules:
  - <rule 1 quoted from official text>
  - <rule 2 ...>
official_examples:
  - <example block as written in docs>
warnings:
  - <any "Important" / "Note" / "Warning" callouts from the docs>

Verification: YAML parses; source is a valid URL; spec_excerpt is non-empty.

When to Trigger This Skill

Red Flags - STOP

These thoughts mean you're rationalizing. STOP and reconsider:

• "I already know the spec from training data"
• "We just fetched this last week, it can't have changed"
• "The cached SKILL.md text is enough"
• "Paraphrasing the spec is fine, saves tokens"
• "Skip the fetch, the user is in a hurry"

All of these mean: drift is about to happen. Fetch.

Common Rationalizations

References

• Master index: https://code.claude.com/docs/llms.txt — the only source of truth

This skill intentionally keeps no static URL table. llms.txt is small (~5KB) and Anthropic restructures docs occasionally; fetching the live index every time is cheaper and safer than maintaining a stale map.