Claude Co-Commands Plugin

3 collaboration commands for Claude Code that use the Codex MCP server to generate parallel plans, validate plans, and brainstorm ideas.

Commands

Command	Description	When to Use
/co-brainstorm	Bounce ideas off Codex	Want fast alternative ideas, critiques, and perspectives
/co-plan	Generate a parallel plan via Codex	Want a second opinion on your planning approach
/co-validate	Get a staff engineer review of your plan	Want critical feedback before finalizing a plan

Prerequisites

• Node.js (for npx)
• Claude Code

Installation

Option 1: Plugin Marketplace (Recommended)

# Add the marketplace
/plugin marketplace add SnakeO/claude-co-commands

# Install the plugin
/plugin install co-commands@snakeo-co-commands

Option 2: Git Clone

git clone https://github.com/SnakeO/claude-co-commands.git
# Copy skill folders to ~/.claude/skills/
cp -r claude-co-commands/plugins/co-commands/skills/* ~/.claude/skills/

Option 3: Manual Copy

Copy plugins/co-commands/skills/ contents to ~/.claude/skills/.

MCP Server Setup (Required)

These commands require the Codex MCP server.

Option A: CLI (Recommended)

claude mcp add validate-plans-and-brainstorm-ideas -- npx -y @openai/codex mcp-server

Option B: Manual

Add this to the mcpServers object in ~/.claude.json:

"validate-plans-and-brainstorm-ideas": {
  "command": "npx",
  "args": ["-y", "@openai/codex", "mcp-server"]
}

If you already have entries in mcpServers, merge this as an additional key. Do not overwrite existing servers.

Verify

1. Restart Claude Code (if you edited ~/.claude.json manually).
2. Run claude mcp list to confirm the server is registered.
3. Test with /co-brainstorm test idea and confirm it triggers the MCP call.

Command Details

/co-brainstorm

Starts an interactive brainstorming session with Codex. Pass your topic or question as the argument.

/co-brainstorm how should we structure the authentication system

Supports follow-up conversation to dig deeper into ideas.

/co-plan

Generates an alternative plan in the background while you continue your own planning. Pass your task description as the argument.

/co-plan add user authentication with OAuth2 support

Compare the Codex plan against yours to catch missed approaches, simpler alternatives, or overlooked edge cases.

/co-validate

Sends your plan to Codex for a staff-engineer-style review. Pass the path to your plan file.

/co-validate .claude/plans/my-plan.md

Returns critical issues, simplification opportunities, and alternative approaches. Supports back-and-forth discussion.

Troubleshooting

Problem	Solution
npx: command not found	Install Node.js which includes npm/npx
MCP tool not found in session	Verify the server name is exactly validate-plans-and-brainstorm-ideas in ~/.claude.json
JSON parse errors in ~/.claude.json	Validate your JSON (check commas and braces)
Commands not appearing after install	Restart Claude Code and verify skill folders exist

License

MIT