Meatspace MCP Server

MeatSpace

Human-in-the-loop service for AI agents. When an agent hits a subjective, high-stakes, or ambiguous decision, MeatSpace routes it to a human who picks one of 2–4 options and returns a structured result.

Live at meatspace.run

What it does

An agent posts a title, optional content (text, markdown, HTML, or an image), and 2–4 labeled choices. A human reviewer is shown the request, picks one, and the API returns the selected id and label. The agent waits via long-poll or webhook.

Typical use cases:

• Approval gates before destructive or irreversible actions (deploys, deletes, payments).
• Subjective tie-breaks where the model is below its confidence threshold.
• Tasteful judgment calls — copy choices, design preferences, ranking ties.
• Escalation when an agent has run out of deterministic checks.

Don't use it when the task is deterministic, automatically verifiable, or low-stakes and easily reversible.

Three integration methods

All three sit on the same backing API and accept the same Bearer token.

Zero-setup self-service flow

A new agent can fully onboard itself in three calls — no signup page, no approval queue, no human in the setup loop:

1. POST /api/keys with {"name": "your-agent", "email": "owner@example.com"} → returns an API key instantly. Rate-limited to 5 keys per email.
2. POST /api/requests with the Bearer token, your title, and choices → creates the review request.
3. GET /api/requests/{id}/wait → blocks until the human responds, or times out and returns pending with a review_url and poll_url.

The same flow is available over MCP: initialize → tools/list → provision_api_key → ask_human. The provision_api_key and get_service_status tools require no auth, so a fresh MCP client can connect without credentials and bootstrap itself.

REST quickstart

Provision a key:

curl -X POST https://meatspace.run/api/keys \
  -H "Content-Type: application/json" \
  -d '{"name": "my-agent", "email": "you@example.com"}'

The response includes api_key — shown once, save it. All subsequent calls use Authorization: Bearer <token>.

Create a request:

curl -X POST https://meatspace.run/api/requests \
  -H "Authorization: Bearer $MEATSPACE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "agent_name": "my-agent",
    "title": "Ship v2.0 to production?",
    "content": "All tests pass. Staging looks good. 2 minor lint warnings.",
    "choices": [
      { "id": "ship", "label": "Ship it" },
      { "id": "wait", "label": "Wait for next cycle" }
    ],
    "confidence": 0.7,
    "consequence_of_wrong_choice": "Premature ship affects ~50k users"
  }'

Response:

{
  "success": true,
  "data": {
    "id": "uuid",
    "status": "pending",
    "review_url": "https://meatspace.run/review/uuid?token=opaque-review-token",
    "poll_url": "/api/requests/uuid",
    "expires_at": "2026-04-23T19:00:00.000Z"
  }
}

Long-poll for the result:

curl https://meatspace.run/api/requests/{id}/wait?timeout=25000 \
  -H "Authorization: Bearer $MEATSPACE_API_KEY"

Returns { status: "completed", selected, selected_label, responded_at } when the human responds, or 202 if still pending.

Optional fields on POST /api/requests: content_type (text default, markdown, html, image), decision_reason, confidence (0–1), consequence_of_wrong_choice, recommended_option, callback_url (must be HTTPS and host-allowlisted), metadata (passed through to the webhook), run_id, trace_id, timeout_seconds (default 3600, max 86400).

MCP

MeatSpace implements MCP over Streamable HTTP at https://meatspace.run/api/mcp. The server exposes three tools:

• get_service_status — availability and escalation guidance. No auth.
• provision_api_key — mint a Bearer token. No auth, rate-limited.
• ask_human — submit a decision. Requires Bearer auth.

Claude Code config:

{
  "mcpServers": {
    "meatspace": {
      "type": "url",
      "url": "https://meatspace.run/api/mcp",
      "headers": {
        "Authorization": "Bearer <your-api-key>"
      }
    }
  }
}

ask_human long-polls for up to 20 seconds. If the human hasn't responded by then, the tool returns status: "pending" with a review_url (for the human) and a poll_url (for the agent).

Browser SDK

For agents running in browser contexts:

<script type="module">
  import { MeatSpace } from 'https://meatspace.run/sdk/meatspace.js';

  const ms = new MeatSpace();
  await ms.getKey({ name: 'browser-agent', email: 'agent@example.com' });

  const result = await ms.ask({
    agentName: 'browser-agent',
    title: 'Which option?',
    choices: [
      { id: 'a', label: 'A' },
      { id: 'b', label: 'B' },
    ],
  });
  console.log(result.selected);
</script>

Methods: getKey(), createRequest(), pollResult(), waitForResult(), ask() (create + wait).

Webhooks

If callback_url is set on the request, MeatSpace POSTs the result when the human responds:

{
  "event": "request.completed",
  "request_id": "uuid",
  "selected": "ship",
  "selected_label": "Ship it",
  "responded_at": "2026-04-23T18:10:00.000Z",
  "metadata": {}
}

callback_url must be https:// and the hostname must be explicitly allowlisted by the operator. If no allowlist is configured, request creation rejects callback URLs. Each delivery is signed with X-HITL-Timestamp and X-HITL-Signature headers.

Discovery endpoints

Errors

All errors return:

{
  "success": false,
  "error": "Human-readable message",
  "code": "machine_readable_code"
}

Common codes: agent_name_required, invalid_choice_count, content_too_large, callback_url_not_allowed, request_create_failed.

Local development

This repo is a Next.js 14 app deployed on Cloudflare Pages.

npm install
npm run dev          # local dev at http://localhost:3000
npm run test         # integration tests
npm run build:cf     # build for Cloudflare Pages
npm run deploy:cf    # build and deploy

Supabase is the system of record for keys and requests; Resend handles transactional email.

License

MIT