ysyecust/documentation-lookup

Documentation Lookup (Context7)

When the user asks about libraries, frameworks, or APIs, fetch current documentation via the Context7 MCP (tools resolve-library-id and query-docs) instead of relying on training data.

Core Concepts

• Context7: MCP server that exposes live documentation; use it instead of training data for libraries and APIs.
• resolve-library-id: Returns Context7-compatible library IDs (e.g. /vercel/next.js) from a library name and query.
• query-docs: Fetches documentation and code snippets for a given library ID and question. Always call resolve-library-id first to get a valid library ID.

When to use

Activate when the user:

• Asks setup or configuration questions (e.g. "How do I configure Next.js middleware?")
• Requests code that depends on a library ("Write a Prisma query for...")
• Needs API or reference information ("What are the Supabase auth methods?")
• Mentions specific frameworks or libraries (React, Vue, Svelte, Express, Tailwind, Prisma, Supabase, etc.)

Use this skill whenever the request depends on accurate, up-to-date behavior of a library, framework, or API. Applies across harnesses that have the Context7 MCP configured (e.g. Claude Code, Cursor, Codex).

How it works

Step 1: Resolve the Library ID

Call the resolve-library-id MCP tool with:

• libraryName: The library or product name taken from the user's question (e.g. Next.js, Prisma, Supabase).
• query: The user's full question. This improves relevance ranking of results.

You must obtain a Context7-compatible library ID (format /org/project or /org/project/version) before querying docs. Do not call query-docs without a valid library ID from this step.

Step 2: Select the Best Match

From the resolution results, choose one result using:

• Name match: Prefer exact or closest match to what the user asked for.
• Benchmark score: Higher scores indicate better documentation quality (100 is highest).
• Source reputation: Prefer High or Medium reputation when available.
• Version: If the user specified a version (e.g. "React 19", "Next.js 15"), prefer a version-specific library ID if listed (e.g. /org/project/v1.2.0).

Step 3: Fetch the Documentation

Call the query-docs MCP tool with:

• libraryId: The selected Context7 library ID from Step 2 (e.g. /vercel/next.js).
• query: The user's specific question or task. Be specific to get relevant snippets.

Limit: do not call query-docs (or resolve-library-id) more than 3 times per question. If the answer is unclear after 3 calls, state the uncertainty and use the best information you have rather than guessing.

Step 4: Use the Documentation

• Answer the user's question using the fetched, current information.
• Include relevant code examples from the docs when helpful.
• Cite the library or version when it matters (e.g. "In Next.js 15...").

Examples

Example: Next.js middleware

1. Call resolve-library-id with libraryName: "Next.js", query: "How do I set up Next.js middleware?".
2. From results, pick the best match (e.g. /vercel/next.js) by name and benchmark score.
3. Call query-docs with libraryId: "/vercel/next.js", query: "How do I set up Next.js middleware?".
4. Use the returned snippets and text to answer; include a minimal middleware.ts example from the docs if relevant.

Example: Prisma query

1. Call resolve-library-id with libraryName: "Prisma", query: "How do I query with relations?".
2. Select the official Prisma library ID (e.g. /prisma/prisma).
3. Call query-docs with that libraryId and the query.
4. Return the Prisma Client pattern (e.g. include or select) with a short code snippet from the docs.

Example: Supabase auth methods

1. Call resolve-library-id with libraryName: "Supabase", query: "What are the auth methods?".
2. Pick the Supabase docs library ID.
3. Call query-docs; summarize the auth methods and show minimal examples from the fetched docs.

Best Practices

• Be specific: Use the user's full question as the query where possible for better relevance.
• Version awareness: When users mention versions, use version-specific library IDs from the resolve step when available.
• Prefer official sources: When multiple matches exist, prefer official or primary packages over community forks.
• No sensitive data: Redact API keys, passwords, tokens, and other secrets from any query sent to Context7. Treat the user's question as potentially containing secrets before passing it to resolve-library-id or query-docs.