Codex MCP Config Format Matrix

Goal

Generate correct Codex MCP snippets without mixing conventions from other clients.

When to Use

• A task adds or edits Codex snippets in profile index pages.
• A review checks Codex CLI or TOML examples.

Rules

1. For Codex TOML in [mcp_servers.<name>] sections:
   • with bearer auth, use bearer_token_env_var = "<ENV_VAR_NAME>" - do not encode bearer auth in TOML as Authorization header values.
   • when bearer_token_env_var is set, do not duplicate the same variable in env_vars.
   • with custom header, use http_headers = { "Header-Name" = "value" }.
   • with custom header that uses environment variable as a value, use env_http_headers = { "Header-Name" = "<ENV_VAR_NAME>" }.
   • for environment variables mapping from host, use env_vars =["<ENV_VAR_NAME>", ...].
2. For Codex CLI:
   • with bearer auth which uses defined environment variable as a token, use --bearer-token-env-var <ENV_VAR_NAME>.
   • don't generate CLI snippet other than OAuth or bearer auth - pure command line arguments doesn't support custom-header or query authentication types and also doesn't support environment variables mapping from host.
3. env TOML snippets should be used to define environment variables:

   [mcp_servers.<server_name>.env]
   ENV_VAR_NAME = "value"
   

4. Keep Codex snippets client-native:

• TOML snippets use [mcp_servers.<name>].
• CLI snippets use codex mcp add <mcp_server_name> --url "https://..." for HTTP streamable MCP servers and codex mcp add <mcp_server_name> -- npx -y mpc4openapi --profile <profile_name> ... for stdio MCP servers.

5. Keep env placeholders aligned with the target format:

• Codex TOML/CLI uses ${VAR} style values when variable interpolation is shown.

Validation Checklist

• Bearer TOML contains bearer_token_env_var and no embedded bearer header.
• Bearer TOML does not duplicate the bearer variable in env_vars.
• Non-bearer custom headers in TOML are emitted via http_headers.
• Snippet tests cover bearer and query/custom-header paths.

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