Claude API for AI agents, pay per token, no API key or account - POST an Anthropic Message

[
  {
    "scheme": "upto",
    "network": "eip155:8453",
    "payTo": "0xB1eF5415E9D3695e16977B8be422AB7512F788C0",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "250000",
    "maxTimeoutSeconds": 120
  }
]

{
  "bazaar": {
    "info": {
      "input": {
        "body": {
          "max_tokens": 64,
          "messages": [
            {
              "content": "Say hi in five words.",
              "role": "user"
            }
          ],
          "model": "haiku"
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      },
      "output": {
        "example": {
          "content": [
            {
              "text": "Hi there, nice to meet you!",
              "type": "text"
            }
          ],
          "stop_reason": "end_turn",
          "usage": {
            "input_tokens": 12,
            "output_tokens": 8
          }
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "body": {
              "properties": {
                "max_tokens": {
                  "description": "1-4096, default 1024",
                  "type": "integer"
                },
                "messages": {
                  "description": "Anthropic Messages API messages array; first role must be user",
                  "type": "array"
                },
                "model": {
                  "enum": [
                    "haiku",
                    "sonnet",
                    "opus",
                    "claude-haiku-4-5",
                    "claude-sonnet-5",
                    "claude-opus-5"
                  ],
                  "type": "string"
                },
                "system": {
                  "description": "Optional system prompt",
                  "type": "string"
                },
                "tools": {
                  "description": "Optional tool definitions (Anthropic tool-use schema)",
                  "type": "array"
                }
              },
              "required": [
                "messages"
              ]
            },
            "bodyType": {
              "enum": [
                "json",
                "form-data",
                "text"
              ],
              "type": "string"
            },
            "method": {
              "enum": [
                "POST"
              ],
              "type": "string"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method",
            "bodyType",
            "body"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {
              "type": "object"
            },
            "type": {
              "type": "string"
            }
          },
          "required": [
            "type"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    }
  }
}

curl "https://clink-lithium-vault.fly.dev/llm/chat"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://clink-lithium-vault.fly.dev/llm/chat");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://clink-lithium-vault.fly.dev/llm/chat")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header