code-explainer-mcp: Instructions file for Claude Code

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project

MCP (Model Context Protocol) server running as a Cloudflare Worker. It explains source code (ASCII architecture diagram, core functionality, component breakdown) using regex/pattern matching only — no LLM calls and no external runtime dependencies. All logic lives in the single file src/index.ts: the default fetch export authenticates the request and dispatches to the module-private explainCode function and its helpers. There is no WorkerEntrypoint class (see "MCP tooling" below).

Commands

• Dev server: npm run dev (alias npm start) — wrangler dev on http://localhost:8787
• Deploy: npm run deploy — runs workers-mcp docgen src/index.ts then wrangler deploy
• Regenerate binding types: npm run cf-typegen (wrangler types) — run after changing bindings/vars in wrangler.jsonc; it rewrites worker-configuration.d.ts
• Tests: npm test (Vitest run via @cloudflare/vitest-pool-workers; npm run test:watch for watch mode) — the suite in test/index.spec.ts drives the Worker through SELF.fetch (info page incl. HEAD, auth + fail-closed guard, the explainCode contract for JS/Python, request validation). The test secret is injected via vitest.config.mts (miniflare bindings), overriding the placeholder.
• Typecheck: no script — npx tsc --noEmit checks src/ (root tsconfig.json excludes test/); type-check the tests with npx tsc -p test/tsconfig.json --noEmit
• Lint: npm run lint (eslint .); auto-fix with npm run lint:fix
• Format: no script — use npx prettier --write . (a Write|Edit hook in .claude/settings.json also formats changed files)

MCP tooling (known discrepancy)

Despite the project name, src/index.ts does not use workers-mcp at runtime: it implements the endpoint directly with a default fetch export and a custom { method, params } body, not the MCP JSON-RPC wire protocol. workers-mcp is a devDependency (build/deploy-time only) and npm run deploy still runs workers-mcp docgen src/index.ts before wrangler deploy, but there is no WorkerEntrypoint class for docgen to derive tool schemas from. Treat the dependency and the docgen step as vestigial unless the Worker is rewritten onto WorkerEntrypoint. The function-level JSDoc in src/index.ts is ordinary documentation — keep it accurate, but docgen does not consume it today.