# SandBase Harness

A stdio bridge connecting AI coding assistants to the SandBase Harness runtime for session control, turn handling, and sandboxed tool execution.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 635
- Author: sandbaseai
- License: Apache-2.0 · policy=link-only · description only; the file stays with the author
- Source: https://github.com/sandbaseai/sandbase-harness
- Updated: 2026-10-18
- HTML: https://affpapa.org/en/nevibecode/mcp/sandbase-harness

## What it does

This MCP bridge maps client requests to the SandBase Harness platform via standard input/output. It exposes controls for agent sessions, execution turns, artifact retrieval, and task cancellation. The runtime stores its metadata in a local SQLite database.

Code can execute in several environments: host processes, dedicated Docker containers per session, Kubernetes pods, or custom worker queues. Supported model backends include Anthropic, OpenAI, MiniMax, and OpenAI-compatible endpoints like DeepSeek.

Because the bridge image `ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8` runs via Docker, Docker must be active on your machine. The bridge fails immediately if `MANAGED_AGENTS_URL` and `MANAGED_AGENTS_API_KEY` do not point to a reachable Harness instance.

## Requirements
- Needs: Docker
- Environment variables: `MANAGED_AGENTS_URL`, `MANAGED_AGENTS_API_KEY` — keys and tokens: ask the human for the values, never commit them or put them in shared files.

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add --env MANAGED_AGENTS_URL=<MANAGED_AGENTS_URL> --env MANAGED_AGENTS_API_KEY=<MANAGED_AGENTS_API_KEY> --transport stdio sandbase-harness -- docker run -i --rm -e MANAGED_AGENTS_URL -e MANAGED_AGENTS_API_KEY ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8
```
Replace <…> with your own values

### Codex

**Platform CLI**
```bash
codex mcp add sandbase-harness --env MANAGED_AGENTS_URL=<MANAGED_AGENTS_URL> --env MANAGED_AGENTS_API_KEY=<MANAGED_AGENTS_API_KEY> -- docker run -i --rm -e MANAGED_AGENTS_URL -e MANAGED_AGENTS_API_KEY ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8
```
Replace <…> with your own values

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "sandbase-harness": {
            "command": "docker",
            "args": [
                "run",
                "-i",
                "--rm",
                "-e",
                "MANAGED_AGENTS_URL",
                "-e",
                "MANAGED_AGENTS_API_KEY",
                "ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8"
            ],
            "env": {
                "MANAGED_AGENTS_URL": "<MANAGED_AGENTS_URL>",
                "MANAGED_AGENTS_API_KEY": "<MANAGED_AGENTS_API_KEY>"
            }
        }
    }
}
```
Replace <…> with your own values

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "sandbase-harness": {
            "type": "stdio",
            "command": "docker",
            "args": [
                "run",
                "-i",
                "--rm",
                "-e",
                "MANAGED_AGENTS_URL",
                "-e",
                "MANAGED_AGENTS_API_KEY",
                "ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8"
            ],
            "env": {
                "MANAGED_AGENTS_URL": "<MANAGED_AGENTS_URL>",
                "MANAGED_AGENTS_API_KEY": "<MANAGED_AGENTS_API_KEY>"
            }
        }
    }
}
```
Replace <…> with your own values

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add -e MANAGED_AGENTS_URL=<MANAGED_AGENTS_URL> -e MANAGED_AGENTS_API_KEY=<MANAGED_AGENTS_API_KEY> sandbase-harness docker run -i --rm -e MANAGED_AGENTS_URL -e MANAGED_AGENTS_API_KEY ghcr.io/sandbaseai/sandbase-harness-mcp:0.3.8
```
Replace <…> with your own values

## When to use it
- isolate generated code execution inside Docker or Kubernetes containers
- handle persistent agent sessions and review turn history
- stop runaway processes and inspect generated artifacts
- manage tool permissions and API credentials locally

## Example prompts
- Create a new agent session in SandBase Harness and execute the prompt
- Check the status of the current turn and retrieve generated artifacts
- Cancel the active task running in SandBase Harness

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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