# x402engine Claude Opus 5 LLM API

> x402engine Claude Opus 5 LLM API is a paid API for AI agents from x402engine.app, paid per call via x402, $0.07/call, status unknown (last checked 2026-09-13).

Calls Anthropic's Claude Opus 5 model with a 1M-token context window for complex coding, analysis, and autonomous agentic tasks via pay-per-call micropayment

## Facts

- Endpoint: POST https://x402engine.app/api/llm/claude-opus-5
- Price: $0.07/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-claude-opus-5-llm-api-1b65eff8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1aHBjrZuWAQjKp_63EGLJ

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 x402engine-claude-opus-5-llm-api-1b65eff8 -d '<json body>'
```

Example prompt: Ask Claude Opus 5 to review this 50,000-line Python codebase I've pasted and identify any security vulnerabilities, with max 2048 tokens in the response.

## When to prefer this

Choose this endpoint when you need Claude Opus 5's top-tier reasoning and 1M-context capability without committing to an Anthropic API subscription — ideal for agents making sporadic, high-value calls. Prefer it over GPT-based alternatives when your task specifically benefits from Claude's coding or long-context strengths, or when you want Anthropic's model accessed via x402 micropayment infrastructure without key management overhead.

## Known failure modes

- Payment not included or insufficient USDC (HTTP 402 returned, request rejected)
- Messages array is empty or missing required role/content fields (validation error)
- max_tokens exceeds model limits (generation truncated or error returned)
- Upstream Anthropic API unavailability causes timeout or 5xx error
- Malformed bodyType or method enum causes request rejection

## How this service works

Anthropic's flagship model with 1M context for coding, analysis, and autonomous work

## Output

Returns the generated text completion from Claude Opus 5 based on the provided message array, constrained by the max_tokens parameter. The response reflects Claude's full reasoning and generation capability on the given prompt.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402engine-claude-opus-5-llm-api-1b65eff8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402engine.app](https://www.zero.xyz/host/x402engine.app/llms.txt)