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Inspector ​

Problem ​

You want to explore all available tools interactively, test tool calls with different arguments, and verify the server is wired up correctly before integrating with an AI client.

Solution ​

Build the server and run it through the MCP Inspector for an interactive UI. Use HTTP mode during integration testing to inspect raw request and response payloads.

Interactive inspection with MCP Inspector ​

sh
cd packages/codex
pnpm build
npx @modelcontextprotocol/inspector node dist/cli.js

The Inspector opens a browser UI where you can browse tools, call them with custom arguments, and view the raw MCP protocol messages.

HTTP mode for integration debugging ​

sh
cd packages/codex
pnpm build
node dist/cli.js --port 3100

Verify the server is up:

sh
curl http://localhost:3100/health
# {"status":"ok"}

Then connect any MCP client or send raw HTTP requests to http://localhost:3100/.

Pitfalls ​

  • The Inspector requires a built dist/cli.js. Run pnpm build in packages/codex first; inspecting the source directly will fail.
  • HTTP mode binds to 0.0.0.0 by default. Do not expose the port publicly in development environments.
  • The MCP Inspector version must be compatible with MCP SDK v1.x. Use npx @modelcontextprotocol/inspector without a pinned version to get the latest compatible release.