# ClinkAgent Keyless Claude API

> ClinkAgent Keyless Claude API is a paid API for AI agents from clinkagent.com, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-02).

Proxy endpoint for Anthropic Claude models (Haiku, Sonnet, Opus) — accepts standard Anthropic Messages API requests without requiring an API key, billing per token via x402 micropayments

## Facts

- Endpoint: POST https://clinkagent.com/llm/chat?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/clinkagent-keyless-claude-api-75638f46
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FDivv_5vikJlictgiilAt

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 clinkagent-keyless-claude-api-75638f46 -d '<json body>'
```

Example prompt: Send this conversation to Claude Sonnet 5 — system prompt is 'You are a helpful assistant', user message is 'Explain quantum entanglement in two sentences', max 300 tokens — no API key needed, just pay per token.

## When to prefer this

Choose this endpoint when your agent needs to call Claude (Haiku, Sonnet, or Opus) without managing an Anthropic API key or account, especially in agentic or serverless contexts where x402 micropayment billing is preferred. Ideal for one-off inference calls, agent pipelines that need tool/function calling support, or developers who want pay-as-you-go access at list price + 25% without a subscription commitment.

## Known failure modes

- Insufficient USDC balance for x402 payment — payment required error returned
- Invalid model enum value — request rejected with validation error
- messages array missing or first role not 'user' — Anthropic API validation error
- max_tokens exceeds 4096 — capped or rejected
- Tool definition schema malformed — Anthropic tool-use error propagated
- Request cost exceeds $0.25 cap — call may be rejected or truncated

## How this service works

Claude API for AI agents, pay per token, no API key or account - POST an Anthropic Messages request (messages, system, tools, tool_choice, thinking) and get the full response back. Claude Opus 5, Sonnet 5, Haiku 4.5. Tool calling / function calling supported. Billed on actual usage at list price + 25%, capped at $0.25 per call (x402 upto scheme). LLM inference, chat completions, keyless Claude, Anthropic proxy. Free price sheet: /llm/models.

## Output

Full Anthropic Messages API response object including the assistant's message content, stop reason, tool use blocks if tools were invoked, and token usage counts (input and output tokens consumed).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "enum": [
    "haiku",
    "sonnet",
    "opus",
    "fable",
    "claude-haiku-4-5",
    "claude-sonnet-5-5",
    "claude-opus-5-5",
    "claude-fable-5-1"
   ],
   "type": "string"
  },
  "tools": {
   "type": "array",
   "description": "Optional tool definitions (Anthropic tool-use schema)"
  },
  "system": {
   "type": "string",
   "description": "Optional system prompt"
  },
  "messages": {
   "type": "array",
   "description": "Anthropic Messages API messages array; first role must be user"
  },
  "max_tokens": {
   "type": "integer",
   "description": "1-4096, default 1024"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "usage": {
   "input_tokens": 12,
   "output_tokens": 8
  },
  "content": [
   {
    "text": "Hi there, nice to meet you!",
    "type": "text"
   }
  ],
  "stop_reason": "end_turn"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/clinkagent-keyless-claude-api-75638f46/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from clinkagent.com](https://www.zero.xyz/host/clinkagent.com/llms.txt)