Test, Debug, Iterate

Outcome

Set up a fast debugging loop so MCP issues are easy to diagnose.

Common Failure Modes

1. Build output missing (dist/index.js does not exist).
2. Wrong command/path in Codex MCP config.
3. Tool listed but argument shape mismatches schema.
4. Unhandled runtime errors inside tool handlers.

Quick Debug Checklist

1. Rebuild:

pnpm --filter @create-something/codex-demo-mcp build

2. Confirm output file exists:

ls packages/codex-demo-mcp/dist

3. Confirm Codex points to the right server command:

codex mcp get codex-demo

4. Add temporary logs in src/index.ts:

console.error('[codex-demo-mcp] tool call', request.params.name, request.params.arguments);

5. Restart Codex session and run the same prompt again.

Add One Real Tool

After echo_text, add a tool tied to your daily work. Example:

• list_workspace_packages
• find_todos
• summarize_changed_files

Keep each tool focused and deterministic.

Next

Continue to Ship and Extend.