MCP servers

The built-in tools cover your files and your shell. MCP is how everything else gets in: a database, a ticket tracker, an internal service.

An MCP server is a separate program that exposes tools. You register it once and its tools join the list Codex can use.

codex mcp add sqlite -- npx -y @modelcontextprotocol/server-sqlite --db-path ./links.db

Added global MCP server 'sqlite'.

Everything after the double dash is the command that starts the server. That is a real run, and here is the configuration it wrote:

[mcp_servers.sqlite]
command = "npx"
args = ["-y", "@modelcontextprotocol/server-sqlite", "--db-path", "./links.db"]

Which means you can also write it by hand, and commit a project's servers in .codex/config.toml so a colleague gets the same tools by cloning.

Checking what is connected

codex mcp list

Name    Command  Args                                                         Status   Auth
sqlite  npx      -y @modelcontextprotocol/server-sqlite --db-path ./links.db  enabled  Unsupported

Name, how it starts, whether it is enabled, and whether it supports authentication. When a tool you expected is missing, this is the first place to look.

codex mcp list

No MCP servers configured yet. Try `codex mcp add my-tool -- my-command`.

And that is the same command after removing it again, which is what a clean machine looks like.

Remote servers

A server does not have to be a local command. --url registers a remote one, with OAuth details where the service needs them, which is how hosted tools are added without running anything yourself.