# Harness

An MCP server for the Harness environment. It allows coding agents to start Claude Code or Codex runs across connected machines, wait for completion, and read results.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed · ★ 1360
- Author: autonomous-ai
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/autonomous-ai/openharness
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/mcp/harness

## What it does

The server connects Claude Code and other clients to the Harness workspace. Through MCP, an agent can start external runs of Codex or Claude Code. It waits for progress and reads final outputs. You can orchestrate tasks across several computers.

Execution happens under the Harness daemon. Every session runs inside its own tmux pane. Terminal text moves directly between machines using WebRTC and ChaCha20-Poly1305 encryption. Relays only handle encrypted ciphertext without storing keys.

Launching `@autonomous-ai/harness-mcp` requires `npx`. The server cannot interact with agents unless the Harness daemon is configured on the target hosts.

## Requirements
- Needs: Node.js (commands run via npx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add harness -- npx -y @autonomous-ai/harness-mcp
```

### Codex

**Platform CLI**
```bash
codex mcp add harness -- npx -y @autonomous-ai/harness-mcp
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "harness": {
            "command": "npx",
            "args": [
                "-y",
                "@autonomous-ai/harness-mcp"
            ]
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "harness": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "@autonomous-ai/harness-mcp"
            ]
        }
    }
}
```

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add harness npx -y @autonomous-ai/harness-mcp
```

## When to use it
- run Claude Code and Codex sessions on remote servers
- monitor task execution status across Harness sessions
- collect answers and terminal output from running agents
- manage agent workflows inside isolated tmux panes

## Example prompts
- Start a Claude Code task on the remote machine through Harness and wait for the result.
- Check the status of the Codex session in Harness and read its terminal output.

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md