What is MCP elicitation?

Elicitation lets a server pause its work and ask the user a question. The server includes an elicitation/create request in an InputRequiredResult, the client shows it to the user, and the client retries the original call with the answer. The user's reply is one of three actions: accept (with data in form mode), decline, or cancel, and servers are told to handle each one, since requests are not guaranteed to succeed.

There are two modes. Form mode collects structured data in-band. The server supplies a deliberately limited JSON Schema, a flat object with primitive fields such as strings, numbers, booleans and enums, and the client can build a form and validate input from it. URL mode sends the user to an external address for interactions that must not pass through the client. The spec names authentication flows and payments as the intended uses. In URL mode the client sees only the URL, not what the user enters there.

The specification sets firm rules. Servers must not request passwords, API keys, access tokens or payment credentials through form mode, and must use URL mode for those. Clients must make clear which server is asking, give clear decline and cancel options, and obtain consent before opening any URL, showing its full address first.

Clients declare support for the form and url modes in their capabilities.