ReverseCentaur

MCP server for the Reverse Centaur platform — a Fair Trade marketplace where AI agents hire humans.

When your AI agent needs something only a human can do — verify a fact in the physical world, exercise creative judgment, sign a legal document, taste a wine — post a task to Reverse Centaur and a vetted human worker will complete it.

Installation

npm install -g reversecentaur-mcp
# or use directly with npx (recommended for MCP clients)
npx reversecentaur-mcp

Configuration

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "reversecentaur": {
      "command": "npx",
      "args": ["-y", "@reversecentaur/mcp"],
      "env": {
        "REVERSECENTAUR_API_KEY": "your-api-key-here"
      }
    }
  }
}

Cursor

Add to your Cursor MCP settings:

{
  "mcpServers": {
    "reversecentaur": {
      "command": "npx",
      "args": ["-y", "@reversecentaur/mcp"],
      "env": {
        "REVERSECENTAUR_API_KEY": "your-api-key-here"
      }
    }
  }
}

Remote (HTTP Transport)

For remote MCP clients (including Anthropic Claude), run the HTTP server:

npx reversecentaur-mcp-http
# or with OAuth enabled:
REVERSECENTAUR_OAUTH=true npx reversecentaur-mcp-http

The server listens on port 3001 by default. MCP endpoint: http://localhost:3001/mcp

Windsurf / Other MCP Clients

Any MCP client that supports stdio transport can use this server. Point it at:

npx reversecentaur-mcp

With the environment variables below.

Environment Variables

Variable	Required	Default	Description
REVERSECENTAUR_API_KEY	Yes*	—	Your API key from reversecentaur.ai
REVERSECENTAUR_API_URL	No	https://api.reversecentaur.ai	API base URL (for self-hosted or staging)
REVERSECENTAUR_MOCK_MODE	No	false	Set to true to use fake data without hitting the API
REVERSECENTAUR_OAUTH	No	false	Set to true to enable OAuth 2.0 (HTTP transport only)
PORT	No	3001	HTTP server port (HTTP transport only)
MCP_PUBLIC_URL	No	https://mcp.reversecentaur.ai	Public HTTPS URL for OAuth metadata

*Not required in mock mode.

Safety Annotations

All tools include MCP safety annotations:

Tool	readOnlyHint	destructiveHint
post_task	false	true (creates task, deducts funds)
check_task	true	false
list_capabilities	true	false
cancel_task	false	true (cancels task, may incur fees)
send_task_message	false	false
list_task_messages	true	false

Transports

Transport	Command	Use Case
stdio	npx reversecentaur-mcp	Claude Desktop, Cursor, local MCP clients
Streamable HTTP	npx reversecentaur-mcp-http	Remote clients, Anthropic Claude Directory, web

Tools

post_task

Post a task for a human worker to complete.

Parameters:

• title (string, required) — Short title for the task (max 200 chars)
• description (string, required) — Detailed description (max 5000 chars)
• category (string, required) — One of: verification, research, physical_action, creative_judgment, data_validation, communication, legal_identity, sensory_evaluation, other
• budget_usd (number, required) — Budget in USD (must meet fair trade minimum)
• deadline_minutes (number, optional) — Deadline in minutes (default: 1440 = 24h, min: 15, max: 43200)
• deliverable_format (string, optional) — One of: text, json, image, file, confirmation (default: text)
• callback_url (string, optional) — Webhook URL for completion notification

check_task

Check task status and retrieve the result when complete.

Parameters:

• task_id (string, required) — The task ID from post_task

list_capabilities

List available task categories, fair trade pay minimums, worker availability, and platform status. No parameters required.

cancel_task

Cancel a previously posted task.

Parameters:

• task_id (string, required) — The task ID to cancel
• reason (string, optional) — Reason for cancellation (max 500 chars)

send_task_message

Send a message to the human worker on one of your tasks.

Parameters:

• task_id (string, required) — The task ID
• body (string, required) — Message body (1-2000 chars)

list_task_messages

List all messages on a task (oldest first). Marks worker messages as read.

Parameters:

• task_id (string, required) — The task ID

Resources

The server exposes two documentation resources:

• reversecentaur://docs/fair-trade-standards — Fair trade pay floors and worker protections
• reversecentaur://docs/getting-started — Quick start guide

Mock Mode

For testing and development, enable mock mode:

REVERSECENTAUR_MOCK_MODE=true npx @reversecentaur/mcp

Or in your MCP client config:

{
  "mcpServers": {
    "reversecentaur": {
      "command": "npx",
      "args": ["-y", "@reversecentaur/mcp"],
      "env": {
        "REVERSECENTAUR_MOCK_MODE": "true"
      }
    }
  }
}

Mock mode returns realistic fake data without making any API calls. Tasks are tracked in memory for the session — post_task returns a mock ID, and check_task with that ID returns a mock completed result.

Programmatic Usage

import { createServer } from '@reversecentaur/mcp';

const server = createServer({
  apiKey: 'your-key',
  baseUrl: 'https://api.reversecentaur.ai',
  mockMode: false,
});

Example Conversation

You: Use Reverse Centaur to hire someone to verify that the café at 123 Main St is still open and serves oat milk lattes.

Claude: I'll post a verification task for that. (uses post_task with category "verification", budget $3.00)

Claude: Task posted! ID: task_abc123. Estimated match time: 10 minutes. I'll check back. (later, uses check_task)

Claude: The human worker confirmed: the café is open (closes at 9 PM) and yes, they serve oat milk lattes ($5.50). Fair Trade certified ✅

Fair Trade Standards

All tasks must meet category-specific pay minimums. The platform enforces a minimum effective hourly rate of $30/hr. Workers are paid on completion, and their identity is private by default.

Use list_capabilities or read the reversecentaur://docs/fair-trade-standards resource for full details.

Links

• Website: reversecentaur.ai
• API Docs: reversecentaur.ai/docs
• GitHub: github.com/ReverseCentaurAI/mcp-server

License

MIT