Proofslip

@proofslip/mcp-server

MCP server for ProofSlip — receipt-based verification for AI agent workflows. Create, verify, and poll ephemeral receipts that let agents prove what happened before deciding what happens next.

Tools

create_receipt

Create a receipt to record that something happened. Receipts expire after 24 hours by default.

Parameter	Type	Required	Description
type	enum	Yes	action, approval, handshake, resume, failure
status	string	Yes	Freeform status (e.g. "success", "pending", "failed")
summary	string	Yes	What happened — max 280 chars
payload	object	No	Structured JSON data (max 4KB)
ref	object	No	Workflow references (run_id, agent_id, workflow_id, etc.)
expires_in	number	No	TTL in seconds (60–86400, default 24h)
idempotency_key	string	No	Prevents duplicate receipts on retry
audience	"human"	No	Enrich verify page with social cards

Requires: PROOFSLIP_API_KEY environment variable.

verify_receipt

Verify a receipt and retrieve its full data before deciding what to do next.

Parameter	Type	Required	Description
receipt_id	string	Yes	The receipt ID (starts with rct_)

No API key required.

check_receipt_status

Lightweight status poll — returns only status and polling guidance, no payload.

Parameter	Type	Required	Description
receipt_id	string	Yes	The receipt ID (starts with rct_)

No API key required. Use this instead of verify_receipt when you only need to know if state has changed.

signup

Get a free API key (500 receipts/month).

Parameter	Type	Required	Description
email	string	Yes	Your email address

No API key required.

Usage Example

You: "Create a receipt proving we sent the welcome email"

Agent calls create_receipt:
  type: "action"
  status: "success"
  summary: "Sent welcome email to [email protected]"
  ref: { workflow_id: "onboarding-123", agent_id: "email-agent" }

→ Returns receipt_id, verify_url, is_terminal: true

You: "Verify receipt rct_abc123 before sending the follow-up"

Agent calls verify_receipt:
  receipt_id: "rct_abc123"

→ Returns full receipt: type, status, summary, payload, ref
→ Agent confirms the action happened before proceeding

You: "Check if the approval is still pending"

Agent calls check_receipt_status:
  receipt_id: "rct_def456"

→ Returns: status: "pending", is_terminal: false, next_poll_after_seconds: 30
→ Agent waits 30s then checks again

Setup

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "proofslip": {
      "command": "npx",
      "args": ["-y", "@proofslip/mcp-server"],
      "env": {
        "PROOFSLIP_API_KEY": "ak_your_key_here"
      }
    }
  }
}

Cursor / Windsurf

Add to MCP settings:

{
  "mcpServers": {
    "proofslip": {
      "command": "npx",
      "args": ["-y", "@proofslip/mcp-server"],
      "env": {
        "PROOFSLIP_API_KEY": "ak_your_key_here"
      }
    }
  }
}

Claude Code

claude mcp add proofslip -- npx -y @proofslip/mcp-server

Then set your API key in your environment or .env file.

Configuration

Variable	Required	Description
PROOFSLIP_API_KEY	For creating receipts	Your API key (starts with ak_)
PROOFSLIP_BASE_URL	No	API base URL (default: https://proofslip.ai)

Get an API Key

Use the signup tool from any MCP client, or:

curl -X POST https://proofslip.ai/v1/auth/signup \
  -H "Content-Type: application/json" \
  -d '{"email": "[email protected]", "source": "api"}'

Links

• Live Site
• API Docs
• Example Receipt
• Context Capsule (sister product — execution context for handoffs)
• GitHub

License

MIT