Fetching Claude Docs

---
name: fetching-claude-docs
description: "Fetches the current official Claude Code component spec from code.claude.com, returning verbatim excerpts so designs never drift from stale memory. Use PROACTIVELY before writing or modifying any Claude Code component (subagent, skill, hook, rule, slash command, plugin manifest, settings.json, MCP config). 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.

## Routing

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

## Task Initialization (MANDATORY)

Follow [task initialization protocol](../../references/task-initialization.md).

**Tasks:**
1. Identify component type and question
2. Resolve URL from llms.txt
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):**

```yaml
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

| Trigger | Action |
|---|---|
| User says "create/write/modify a [component]" | Fetch component spec BEFORE design |
| User asks "what's the official way to..." | Fetch relevant docs |
| Reviewer flags a frontmatter field as suspicious | Fetch field spec to confirm |
| Plugin maturity migration | Fetch plugins-reference + plugin-marketplaces |
| Editing settings.json or hooks | Fetch settings + hooks reference |
| Designing model selection or tool restrictions | Fetch sub-agents.md |

## 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

| Excuse | Reality |
|--------|---------|
| "I know the official spec" | Anthropic ships docs updates weekly. Your knowledge is stale by definition. |
| "WebFetch is slow" | 15-min cache makes repeats free. First fetch < 3s. |
| "Just summarize from memory" | Summary = drift source. v7.1's `<law>` removal happened because nobody fetched. |
| "User won't notice" | Reviewer will. Or six months later when official spec changed. |
| "Token cost too high" | Drift cost is higher: rework, breaking changes, false confidence. |

## 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.