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Updated Oct 14, 2025 Codex MCP install docs You can find your Ref API key at ref.tools/keys

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Install

Codex is configured in a config.toml file. This typically lives at ~/.codex/config.toml To enable Ref update your config.toml to include: 
[mcp_servers.ref]
url = "https://api.ref.tools/mcp?apiKey=<your-api-key>"
If you are on an older version of Codex and you get the error Error loading configuration: missing field 'command' in 'mcp_servers.ref' and do not want to update, you can install the stdio server: 
[mcp_servers.ref]
command = "npx"
args = ["-y", "ref-tools-mcp@latest"]
env = { "REF_API_KEY" = "<your-api-key>" }

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Verify

Run the command: 
codex mcp list
You should see: 
➜  codex mcp list
Name  Url                                                        Bearer Token Env Var  Status   Auth
ref   https://api.ref.tools/mcp?apiKey=<your-api-key>.           -                     enabled  Unsupporte

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Get help

If you have any issues, please reach out to help@ref.tools. We’re happy to help you get started!