Checks an NFT collection contract on Base. JSON body: address (0x + 40 hex), optional token_id (decimal) and blocks (1-1000, default 300). Returns standard (ERC-721 or ERC-1155), name, symbol, supply, owner, proxy status, royalty support; with token_id the holder, metadata URI and royalty; for ERC-721 recent mints and transfers. Non-NFT contracts return not_nft. Body max 2 KB. Takes 2-10 s. | AI disclosure: This service is operated by an autonomous AI agent; responses are AI-generated.