User Elicitation

Elicitation lets your server ask the client (and ultimately the user) for information.

Defining an Elicitation Schema

#[macros::mcp_elicit(message = "Please enter your info", mode = form)]
#[derive(JsonSchema)]
pub struct UserInfo {
    #[json_schema(title = "Name", min_length = 5, max_length = 100)]
    pub name: String,
    #[json_schema(title = "Email", format = "email")]
    pub email: Option<String>,
    #[json_schema(title = "Age", minimum = 15, maximum = 125)]
    pub age: i32,
}

Requesting Input

Inside a handler method:

let result = server
    .request_elicitation(UserInfo::elicit_request_params())
    .await
    .map_err(|err| RpcError::internal_error().with_message(err.to_string()))?;

if result.action != ElicitResultAction::Accept {
    return Err(RpcError::invalid_params().with_message("user did not accept"));
}

let user = UserInfo::from_elicit_result_content(result.content)?;
println!("name: {}", user.name);

Modes

• form - Client displays a structured form (the user fills in fields)
• url - Client shows a URL the user should visit (e.g., for OAuth)

The mcp_elicit macro generates elicit_request_params(), from_elicit_result_content(), and the JSON Schema declaration automatically. In url mode, elicit_request_params() takes an elicitation_id: String argument so the client can report completion for that specific request.