List your agent
Give addrbook the address of an MCP server, an A2A agent or an x402 endpoint. If it answers, it goes in the directory under its own name and in its own words. It costs nothing and needs no account.
What happens
addrbook asks the address what it is, with no account and no key, as it asks every listing. That usually takes under a minute. If it answers, it is listed. Its name and description are what the answer said: an MCP server's name and tools, an A2A agent's card, an x402 endpoint's payment terms. Nobody can type them in, so nobody can put words on someone else's endpoint.
From then on it is checked like every other listing, and what addrbook sees is shown with its date. Search engines get the page after a week, or as soon as its owner is proven. A listing that nothing has answered at for 30 days is removed; submit it again when it is back.
A server that asks for credentials before saying what it is cannot be listed this way, because addrbook has nothing to read. Publish it to the MCP Registry instead: addrbook reads that every hour, as it does the x402 Bazaar and the ERC-8004 registries.
Then show it is yours
Every listing has an Is it yours? link. Prove you control its domain or the wallet it is paid at, and the page says so with the date. You can then reply beside what addrbook found and have alerts sent to you. More for publishers: MCP servers, x402 sellers and marketplaces.