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beginner 10 minutes

Publish a pay.json manifest

The manifest is the first thing an agent fetches. This guide walks through writing a minimal pay.json, validating it, and serving it at the well-known path. No payment logic yet — just discoverable pricing.

  1. 1

    Start from the schema

    Declare the mcp_pay version and a link to your Server Card. Pricing and accepts come next.

    { "mcp_pay": "0.1", "server_card": "/.well-known/mcp/server-card.json" }
  2. 2

    Add a pricing rule

    Set a free default and price one tool per_call. The pricing block attaches rules to a default, tools, resources, or prompts.

    "pricing": { "default": { "model": "free" }, "tools": { "get_forecast": { "model": "per_call", "amount": "0.003", "currency": "USD" } } }
  3. 3

    List accepted rails

    Add an accepts array naming each rail you support with its network and pay-to details.

    "accepts": [ { "rail": "x402", "network": "eip155:8453", "asset": "USDC", "pay_to": "0x1234..." } ]
  4. 4

    Serve it at the well-known path

    Publish the file so a GET to /.well-known/mcp/pay.json returns it. It is static, cacheable, and needs no auth to read.

Validate before you ship

  • ▸Use the mcp-pay-cli to validate the manifest against the JSON Schema.
  • ▸Keep the mcp_pay version field accurate — it is a v0.1 draft and the schema is versioned.

More guides in the index, or read the architecture to see the full 402 handshake.