mcp-setup-and-debug

name	mcp-setup-and-debug
description	Configure and debug MCP servers for Claude Code, OpenCode, and Codex CLI, including auth headers, scope, and validation checks. Use when MCP tools fail to connect, when an MCP server returns 401/404/HTML, or when adding a new MCP server to this repo.

MCP Setup And Debug

Claude Code mirror of .codex/skills/mcp-setup-and-debug/SKILL.md.

Overview

Add or fix MCP server configs across Claude Code, OpenCode, and Codex. Confirm endpoints, auth headers, scopes, and validate with each client command.

Workflow

1) Confirm endpoints and auth requirements

• Identify the MCP endpoint and transport. For Langfuse Prompt MCP (US) use https://us.cloud.langfuse.com/api/public/mcp with Basic auth. For Langfuse Docs MCP use https://langfuse.com/api/mcp with no auth.
• Use web search to verify URLs and required headers if unsure.

2) Prepare auth header (when required)

• Use LANGFUSE_PUBLIC_KEY and LANGFUSE_SECRET_KEY in .env.local, then run node scripts/setup-langfuse-mcp-auth.js to generate .opencode/langfuse.mcp.auth, .opencode/langfuse.public, and .opencode/langfuse.secret for OpenCode.
• Codex and Claude Code still expect LANGFUSE_MCP_AUTH in the environment.
• Keep credentials out of repo files.

3) Configure each client

• Claude Code: add entries in .mcp.json at repo root, or use claude mcp add --transport http.
  • HTTP servers reference env vars with the ${VAR:-default} syntax.
  • Validate with claude mcp list and the /mcp slash command inside Claude Code.
• OpenCode: add a remote MCP server in opencode.json under mcp.
  • Include headers and set oauth to false for API key based servers.
  • For local MCP servers that run via uvx, use type: "local" and command: ["uvx", "--python", "3.11", "langfuse-mcp", "--read-only", "--tools", "traces,observations"].
  • Validate with opencode mcp list.
• Codex CLI: add entries in .codex/config.toml or ~/.codex/config.toml.
  • For HTTP servers, use env_http_headers to pull LANGFUSE_MCP_AUTH from the environment.
  • Validate with codex mcp list and the /mcp slash command in the TUI.

4) Debug checklist

• 401 Unauthorized usually means the auth header is missing or malformed.
• HTML or 404 responses often mean the URL is wrong or OAuth was attempted on a non OAuth server.
• For OpenCode, set oauth: false when using API keys.
• Confirm environment variables are available to the client process.

5) Report status

• Summarize which clients connect and which fail.
• Provide the exact error text for each failing client and propose the next fix.