x402serps on OpenSea's ERC-8257 Agent Tool Registry

Two x402serps tools are registered onchain in OpenSea's ERC-8257 Agent Tool Registry on Base: Web Search (toolId 893) and URL Extract (toolId 894). Any agent that browses the registry can find them, read their manifests, and pay per call in USDC with x402. No account or API key needed.

What is the ERC-8257 agent tool registry?

ERC-8257 is a permissionless onchain registry for AI agent tools. Each tool is one HTTPS endpoint with a JSON Schema interface, described by a manifest served at /.well-known/ai-tool/<name>.json. Registering a tool records the manifest URL and its keccak256 hash onchain and assigns a toolId, so an agent can check that the manifest it fetches is exactly the one that was registered. OpenSea indexes the registry and lists tools at opensea.io/tools; see OpenSea's registry docs.

Registry contract on Base: 0x265BB2DBFC0A8165C9A1941Eb1372F349baD2cf1.

Web Search · toolId 893

Send a query and get organic results (position, title, URL, snippet) as JSON from a third-party search provider, with country, language, freshness, date-range and pagination options.

• Endpoint: https://x402serps.com/api/v1/search
• Price: $0.004 per call (up to 10 results; billed per 10 above that), paid in USDC via x402
• Manifest: /.well-known/ai-tool/search.json
• Registration transaction: view on Basescan

URL Extract · toolId 894

Send a URL and get the page back as clean markdown, ready for an agent to read, quote or summarise.

• Endpoint: https://x402serps.com/api/v1/extract
• Price: $0.003 per URL, paid in USDC via x402
• Manifest: /.well-known/ai-tool/extract.json
• Registration transaction: view on Basescan

How agents discover and pay

1. Discover. The agent reads the registry (directly onchain or through OpenSea's tool listings and API) and finds toolId 893 or 894.
2. Verify. It fetches the manifest from x402serps.com and checks its hash against the onchain record. Manifest and endpoint share the same origin, as ERC-8257 requires.
3. Call. It sends a request to the endpoint. Without payment, the API replies with HTTP 402 and the exact price.
4. Pay and retry. The agent signs a USDC payment with x402 (Base or Solana) and retries. Results come back as JSON. Failed calls are not charged.

Pricing

Web search is $0.004 per call and URL extract is $0.003 per URL. You can also buy prepaid card credits, or try it free with 25 trial calls using the X-Trial: 1 header. Full details on the pricing page.

Docs and more ways to connect

API docs · x402 search API · MCP server · Integrations · Guides · OpenAPI · Help