mcp-pay¶

Payment awareness layer for MCP (Model Context Protocol)

mcp-pay extends the MCP ecosystem with payment capabilities. It provides:

Schema — a JSON manifest (mcp-pay.json) for declaring pricing and payment rails
Reference Server — a Rust implementation demonstrating payment-gated MCP tools
Protocol — an HTTP 402 payment flow compatible with x402, MPP, Lightning, and card payments

The Gap mcp-pay Fills¶

Ecosystem	Discovery	Payment
MCP Registry	Tools, resources, prompts	None
x402 Bazaar	After payment	x402 only
Tempo MPP	In-network	MPP only
mcp-pay	At `.well-known`	All rails

mcp-pay bridges these ecosystems by providing a rail-agnostic payment manifest that works with all payment protocols.

Key Design Principles¶

Complementary — works alongside MCP Server Card (SEP-2127)
Rail-agnostic — supports multiple payment protocols
Minimal — only payment-specific fields, no duplication
Cacheable — static manifest, dynamic stats

Where Next¶

Getting Started — clone, build, run the reference server.
Payment Manifest — the mcp-pay.json schema, served at /.well-known/mcp/pay.json.
MCP Server Integration — endpoints exposed by the reference server and how payment gating is wired up.
Payment Flow — the HTTP 402 dance between agent, server, and facilitator.
Payment Rails — supported rails and their status.
Specification — the full draft specification.

Project Structure¶

mcp-pay/
├── crates/
│   ├── mcp-pay-schema/     # Schema types + validation
│   ├── mcp-pay-server/     # Reference implementation
│   └── mcp-pay-cli/        # Registry queries (Phase 2)
├── specs/
│   ├── schema/
│   │   └── pay.schema.json
│   └── mcp-pay-specification.md
└── README.md

License¶

Licensed under either of:

MIT license
Apache License, Version 2.0

at your option.