# Vaaya – Anthropic Claude Messages API (Keyless Pay-Per-Call)

> Vaaya – Anthropic Claude Messages API (Keyless Pay-Per-Call) is a paid API for AI agents from vaaya.ai, paid per call via x402, $1/call, status unknown (last checked 2026-11-05).

Sends messages to Anthropic's Claude models via a keyless pay-per-call proxy, returning Claude's response without requiring an Anthropic API key.

## Facts

- Endpoint: POST https://vaaya.ai/api/run/anthropic/messages?utm_source=zero.xyz
- Price: $1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-05
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vaaya-anthropic-claude-messages-api-keyless-pay-per-call-12bcbef2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zttHcaMnHYApYWwrUICzp

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability vaaya-anthropic-claude-messages-api-keyless-pay-per-call-12bcbef2 -d '<json body>'
```

Example prompt: Ask Claude claude-sonnet-5 to summarize the following text in 3 bullet points, with a max of 500 tokens: 'The Amazon rainforest, often referred to as the lungs of the Earth, plays a crucial role in regulating the global climate by absorbing vast amounts of carbon dioxide.'

## When to prefer this

Choose this endpoint when your agent needs to call Claude without storing or managing an Anthropic API key, wants pay-per-call billing in USDC rather than a subscription, or is operating in an environment where provisioning API credentials is impractical. Ideal for one-off Claude calls, agent pipelines without key management infrastructure, or when you want to pay per use rather than committing to a monthly plan.

## Known failure modes

- Invalid or unsupported model name returns an error
- max_tokens set to 0 or negative rejected by schema validation
- Empty messages array fails required field validation
- Payment failure (insufficient USDC) blocks the call
- Rate limiting or quota exhaustion on the underlying Anthropic account
- Malformed message object in the messages array causes a parse error

## How this service works

Anthropic — Claude Messages API, keyless pay-per-call (price varies by model + tokens). Pass standard /v1/messages params: `model` (e.g. claude-sonnet-5), `max_tokens`, `messages`.

## Output

Returns a standard Anthropic Claude /v1/messages response object containing the assistant's generated reply, usage statistics (input/output tokens), model identifier, stop reason, and message metadata — identical to calling Anthropic's API directly.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "$schema": "http://json-schema.org/draft-07/schema#",
     "required": [
      "model",
      "max_tokens",
      "messages"
     ],
     "properties": {
      "model": {
       "type": "string",
       "minLength": 1
      },
      "messages": {
       "type": "array",
       "items": {
        "type": "object",
        "properties": {},
        "additionalProperties": true
       },
       "minItems": 1
      },
      "max_tokens": {
       "type": "integer",
       "exclusiveMinimum": 0
      }
     },
     "additionalProperties": true
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vaaya-anthropic-claude-messages-api-keyless-pay-per-call-12bcbef2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from vaaya.ai](https://www.zero.xyz/host/vaaya.ai/llms.txt)