lockdocs MCP server

lockdocs

Exact-version library docs from your lockfile — local, offline, no rate limits.

Reads your lockfile. Answers from the docs and type declarations of the exact version you installed. npm · PyPI · crates.io · Go. MCP server + CLI in one Rust binary. No account, no API key. MIT.

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A real terminal: one question, two projects. The zod 3 project gets .strict(), the zod 4 project gets z.strictObject(), each cited to package@version file:line.

Quickstart

npx -y @sylphx/lockdocs setup     # add lockdocs to Claude Code, Codex, Cursor, VS Code, Claude Desktop, Windsurf, Gemini CLI

That's it. setup detects the clients you have, writes their MCP config, and prints every change. Run it again and nothing changes. Then ask your agent something like "Use lockdocs: how do I reject unknown keys with the zod we use?"

From a terminal, inside any project:

npx -y @sylphx/lockdocs zod "reject unknown keys"          # docs for the zod version in your lockfile
npx -y @sylphx/lockdocs api axum::Router::route            # exact signature + doc comment
npx -y @sylphx/lockdocs resolve                            # every pinned version, and whether its docs are here
npx -y @sylphx/lockdocs fetch                              # once: add upstream docs at each version's git tag

Manual MCP config

{
  "mcpServers": {
    "lockdocs": { "command": "npx", "args": ["-y", "@sylphx/lockdocs", "mcp"] }
  }
}

Claude Code: claude mcp add lockdocs -- npx -y @sylphx/lockdocs mcp Codex (~/.codex/config.toml):

[mcp_servers.lockdocs]
command = "npx"
args = ["-y", "@sylphx/lockdocs", "mcp"]

The server answers for the client's workspace root (or its working directory, or LOCKDOCS_ROOT). Every tool also takes root.

Why

Your agent writes code against the library version it remembers, not the one you installed. So it calls .dict() on a pydantic 2 model, cookies() without await on Next.js 15, and /:id routes on axum 0.8. Hosted doc servers help, but they guess the version from the prompt, cap free usage, and cannot see your private packages.

lockdocs takes the version question off the table:

Shortened. The full README is on GitHub.