throng-mcp

An MCP server that lets your agent hand work to another one. Any MCP client can call it, and the task goes to any supported harness.

• Another model's view. A review by another vendor's model, a design critique, a cheaper model for a mechanical pass.
• Second opinions. Hand one agent's result to another: Codex reviews, Claude fixes, Codex checks again, each in its own long-lived session.
• Real sessions, not one-shots. The nested agent keeps running; a follow-up goes to the same agent with everything it already knows.
• Background work. Several agents run at once while you carry on.
• Answers by schema. Pass a JSON Schema and the result comes back as data that fits it, not prose to parse: a list of findings, a verdict, a plan, ready to feed into the next step.

Supported harnesses: Claude Code, Codex, OpenCode (and every model it can reach), Gemini CLI, Cursor CLI, GitHub Copilot CLI. Setup for each is under Install.

Any other ACP agent can be described in the config as a custom harness: its command, and the mode or options that make it auto-approve or ask. throng installs nothing for it and guesses nothing; see Custom harnesses.

Example

You're in Claude Code and have just changed the payment flow.

Ask Codex to find a way this payment flow could charge someone twice. Don't change any files.

Claude calls run_thronglet with agent: "codex/gpt-6-sol:high", a self-contained prompt, the repository path and a schema, so the findings come back as data: file, line, steps to reproduce.

Give the findings to Opus. Have it fix each one, add a test for it and run the tests.

A second run_thronglet, with agent: "claude/opus". Codex's findings go into its prompt; Opus edits the code and runs the tests.

Now show the same Codex session what changed. Can it still make a customer pay twice?

That is send_message into the first session: Codex still has its findings in context and checks the fixes against them instead of starting over.

Any of these calls takes background: true: it returns at once and wait_thronglet collects the result later, which is how several agents work while you carry on.

Install

Three parts, in order: the server, the agents it may run, and the client it is called from. The skill at the end is optional.

claude plugin marketplace add agent-runbooks/throng-mcp
claude plugin install throng@throng-mcp

claude plugin marketplace update throng-mcp
claude plugin update throng@throng-mcp

1. The server

The npm package throng-mcp. Needs node ^22.13 || >=24. Tested with node 24.11.1, claude 2.1.282, codex 0.156.1, opencode 1.18.30.

Two ways to run it:

• npx -y throng-mcp@0.9.1 straight in the client config, below. Nothing to install: npx fetches the package on the first start and caches it. The package has no dependencies, so that is one tarball and nothing else. The version is pinned, so the server changes only when you change it: to update, put the new version from the changelog into the command.

• A global install, then the command is throng-mcp. Starts faster than going through npx. To update, run the install again.

  npm i -g throng-mcp
  

2. The agents to run

Each agent needs its own CLI installed and logged in. throng talks to agents over ACP (Agent Client Protocol); Claude Code and Codex need an ACP adapter, and throng ships none. Install only the agents you want to delegate to.

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... View full README on GitHub