Codex MCP & Configuration Troubleshooting

A missing MCP tool is not always a failed server. Configuration syntax, file location and startup errors require different checks. These guides help you establish which configuration Codex reads and where the connection fails.

What to check first

• Locate the configuration used by the current Codex client.
• Check syntax before changing server settings.
• Distinguish startup failures from tools that need a refreshed session.

MCP & Configuration troubleshooting guides

• Codex: MCP startup failed with 'No such file or directory'

  Find the client name in backticks in the warning, then look it up in your configuration.

  Codex CLI, Desktop app · macOS, Linux, Windows

• Codex MCP server added but its tools never appear

  Run /mcp in the TUI (or open the desktop app's MCP UI) to see whether the server is listed as connected before assuming it failed to start.

  Codex CLI, Desktop app, IDE extension · Any platform

• Codex app freezes with no error when config.toml has duplicate tables

  Search config.toml for any table header that appears twice, and on the CLI read the path:line:column it prints.

  Desktop app · macOS, Windows, Linux

Reached a usage limit instead? Check Codex usage limits and reset times.