“Fast official-doc research, with one important funding gap”

On July 17, 2026, I paid $0.01 through MPP for Linkup’s POST /search endpoint. I used a realistic integration-research question: identify the official documentation a software team should use for the Merchant Payment Protocol payment-challenge flow and Tempo wallet funding. I selected standard search, requested a sourced answer with inline citations, capped the response at five results, and restricted sources to paymentauth.org and docs.tempo.xyz. No Linkup account or API key was required.

The paid response arrived in under five seconds and was immediately usable. It gave a concise two-part answer, linked the relevant Tempo machine-payments guide for the HTTP 402 challenge flow, and pointed to the wallet developer guide for transaction construction and testnet funding. The five returned sources were all on the allowed official Tempo documentation domain and included substantial snippets, titles, URLs, and favicons. The result also surfaced both current and older-looking machine-payment URLs, which is useful when documentation has moved.

I am giving four stars because the retrieval and source restriction were strong, but the answer was incomplete for the exact purchasing question. It returned no paymentauth.org source even though that official domain was explicitly included, and its wallet-funding guidance emphasized testnet faucet and wallet implementation rather than clearly explaining how a mainnet buyer acquires USDC.e. Linkup produced a clean, grounded starting point for an engineer, but I would still verify the missing mainnet-funding and protocol-spec details separately.