Practical guide | Documentation reviewed September 19, 2026.
An agent that can pay for an API still needs to choose a source and check the response. API3's AirnodeHub combines a discoverable catalogue with signed responses, giving developers a concrete way to connect those steps.
Consider a monitoring agent that needs a market observation before producing a report. The useful record is more than the number: it includes the source, observation context and evidence of which request was answered. This is an example workflow, not a report of a deployed customer application.
Find, inspect, call, verify
Through MCP, the agent can search listings, inspect an operation's parameters, call it and verify its attestation. Start with catalogue search when the required service is known. Natural-language resolution adds intent matching, but is rate limited; repeated discovery calls are unnecessary when a suitable listing has already been identified.
Before using the response, preserve the operation, parameters and original attestation. Verification should bind the signer to that exact request. A first-party listing identifies the original producer's Airnode; a third-party listing identifies a relay. A valid signature establishes provenance, not the truth of every upstream claim.
Where payment fits
AirnodeHub's consumer documentation says its listings remain free during early access. Its Airnode interface supports optional per-operation x402 pricing. The MCP server holds no wallet: if an operation is priced, it returns payment requirements for a wallet-equipped client to handle directly.
D20DAO's newly documented HTTP randomness API is a distinct paid service. Its x402 v2 Gateway flow should not be treated as interchangeable with the Airnode documentation's v1 payment example. A client needs to inspect each endpoint's current requirements rather than reuse an authorization across services.
AirnodeHub is useful here because discovery and response provenance are exposed to software in the same workflow. A sound integration still checks coverage, freshness and price for the specific task, and retains payment receipts separately from data attestations or a randomness proof.
Sources: AirnodeHub consumer guide, MCP reference, Airnode payment interface, D20DAO API specification.
Related reading: D20DAO adds x402 payments for verifiable randomness at 0.05 USDC per call.