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Prerequisites

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Configuration

Codex configures MCP servers via a TOML file. Add the following to ~/.codex/config.toml:
bearer_token_env_var takes the name of an environment variable. Codex reads the value at runtime on every request. Make sure LIGHTON_API_KEY is set in your shell environment, you can grab your key from the LightOn Console. To scope the server to a single project instead, place the same snippet in .codex/config.toml at the root of your project.

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Verification

  1. Open Codex and start a session.
  2. Use the /mcp command to list configured servers and verify that lighton appears in the output.
  3. Test the connection with a prompt like:
You’re all set. From any Codex session you can now ask it to search or ingest documents in your LightOn workspaces directly.

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References