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Code with Codex

Use the codex pack to start fast-agent with a coding agent, a Codex-optimised filesystem search sub-agent, WebSocket transport and an apply_patch tool that matches the Codex CLI patch format.

uvx fast-agent-mcp@latest --pack codex

This starts fast-agent pre-configured for a Codex-style coding workflow.

What the codex pack gives you

  • A dev coding agent for interactive software work
  • A bounded rg-first search helper backed by codexspark
  • WebSockets enabled by default for modern Codex/OpenAI models
  • An apply_patch tool with a familiar Codex CLI-style patch signature
  • Preconfigured MCP targets available from /connect

The coding agent has a minimal system prompt plus tools for the shell, filesystem and fast-agent services. AGENTS.md is included automatically if present. Customise the agent by editing .fast-agent/agent-cards/dev.md.

Use /skills to discover, add, remove and update skills. Use /connect to connect to MCP Servers.

Codex authentication

If you want to use the Codex OAuth models directly, authenticate once first:

fast-agent auth codexplan

This stores the token in your OS keyring. After that you can use Codex OAuth model aliases such as:

  • codexplan — GPT-5.3 Codex planning model

If you prefer, you can also run model setup explicitly:

uvx fast-agent-mcp@latest model setup

Installation

fast-agent requires Python 3.13 or above. Install with:

uv tool install -U fast-agent-mcp

Or a specific version of Python:

uv tool install --python 3.13 -U fast-agent-mcp

This installs the fast-agent executable.

Next steps

From the fast-agent prompt:

  • Use /skills to view and manage skills
  • Use /connect to connect to the preconfigured MCP servers
  • Ask the agent to create additional cards in .fast-agent/agent-cards/
  • Switch agents with @
  • Configure compaction, hooks or automation with the available skills