Module 07 · intermediate · 1 hour

MCP Servers

MCP gives Codex typed tools and resources backed by external systems. A good server has narrow capabilities, clear schemas, predictable errors, and least-privilege authentication.

What MCP adds

Tools perform actions or queries. Resources expose readable context. Prompts package reusable interactions. Codex can connect to local stdio servers and supported remote transports.

Tools: Typed operations
Resources: Readable context
Auth: Scoped access

Configure a server

Use the MCP configuration surface or config.toml. Keep credentials in the supported environment or authentication flow rather than committing them.

[mcp_servers.docs]
url = "https://developers.openai.com/mcp"

Inspect status

Open /mcp to see connected servers and diagnose unavailable tools. Validate the transport, authentication, tool list, and error response separately.

/mcp
# inspect server status and exposed tools

Design for safety

Separate read-only and mutating tools, validate inputs server-side, expose precise descriptions, and require confirmation for consequential actions.

Continue learning

Use the official OpenAI Codex documentation as the final reference for current commands, settings, and availability.

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