MCP CLI should expose validation, tool listing, and enable/disable management

Summary

codex mcp can add/list/get/remove/login/logout MCP server entries, but it does not expose the rest of the management operations users need for a practical MCP setup: validate a server, inspect discovered tools/resources, enable/disable a server, or self-register the local codex mcp-server entry.

Evidence

Observed in local checkout /Volumes/VIXinSSD/codex-main at 2be9fd5a93.

codex-rs/cli/src/mcp_cmd.rs defines only these subcommands:

• list
• get
• add
• remove
• login
• logout

The underlying config/runtime already has several pieces needed for richer management:

• McpServerConfig.enabled exists and the connection manager filters on it.
• enabled_tools / disabled_tools, default_tools_approval_mode, required, startup/tool timeouts, OAuth fields, and streamable HTTP transport are represented in config.
• The runtime can list tools, list/read resources, and list resource templates through McpConnectionManager and the list_mcp_resources / list_mcp_resource_templates / read_mcp_resource helper tools.

Because the CLI does not expose validation or toggles, users have to hand-edit ~/.codex/config.toml and start a full session to discover whether a server starts and which tools/resources it exposes.

Expected behavior

Add focused MCP management commands such as:

• codex mcp validate <name>: start the configured server, perform initialize/list calls, and report auth/startup/tool discovery failures.
• codex mcp tools <name> or codex mcp inspect <name>: list discovered tools, resources, and resource templates without starting an agent turn.
• codex mcp enable <name> / codex mcp disable <name>: mutate the existing enabled flag instead of requiring manual TOML edits.
• Optional: codex mcp add-self to register codex mcp-server as a local stdio MCP server for other clients.

Acceptance criteria

• Users can validate a configured MCP server from the CLI without launching an interactive session.
• Users can inspect discovered MCP tools/resources/templates from the CLI.
• Users can toggle configured MCP servers on/off through codex mcp.
• Config writes preserve existing MCP server options such as approval settings, timeouts, OAuth fields, and tool filters.