Elicitation

This guide explains how to use elicitation on the server side to request additional user input or external actions during tool execution.

What is Elicitation?

Elicitation allows a server tool to:

• Request structured user input (forms with schema validation)
• Ask the client to perform an external action (e.g. open a payment URL)
• Pause execution until the elicitation is accepted, rejected, or completed

Typical use cases:

• Collecting contact or configuration data
• User confirmation steps
• Payments or OAuth-style redirects

To use elicitation, inject Context into your tool handler and call the elicit() method with either form of URL elicit request params.

Defining a Form Elicitation

Forms use a JSON schema to define and validate structured input.

#[json_schema(de)]
struct Contact {
    name: String,
    email: String,
    age: u32,
}

With #[json_schema] attribute macro you can control the serialization/deserialization performed by serde for your struct:

• all - Applies also derive(serde::Serialize, serde::Deserialize).
• serde - Applies also derive(serde::Serialize, serde::Deserialize).
• ser - Applies also derive(serde::Serialize).
• de - Applies also derive(serde::Deserialize).

Creating and Sending a Form Request

To create elicit request form params you need to use the ElicitRequestParams::form() method with the following with_contract() that specifies the expected JSON schema.

#[tool]
async fn generate_business_card(mut ctx: Context) -> Result<String, Error> {
    let params = ElicitRequestParams::form(
        "Please provide your contact information"
    )
    .with_schema::<Contact>();

    ctx.elicit(params.into())
        .await?
        .map(format_contact)
}

fn format_contact(c: Contact) -> String {
    format!("Name: {}, Age: {}, email: {}", c.name, c.age, c.email)
}

Execution flow:

1. Server sends a form elicitation request
2. Client receives and validates the data
3. Tool resumes with the validated payload
4. The result is mapped to the tool output

Defining a URL Elicitation

URL elicitations are used when the user must perform an external action. You can create the ElicitRequestUrlParams by leveraging the ElicitRequestParams::url() method.

#[tool]
async fn pay_a_bill(mut ctx: Context) -> Result<&'static str, Error> {
    let params = ElicitRequestParams::url(
        "https://www.paypal.com/us/webapps/mpp/paypal-payment",
        "Please pay your bill using PayPal"
    );

    let elicitation_id = params.id.clone();

    ctx.elicit(params.into()).await?;

    // Send the `notifications/elicitation/complete`
    ctx.complete_elicitation(elicitation_id).await?;

    Ok("Payment successful")
}

You may also send a notifications/elicitation/complete notification when an out-of-band interaction is completed. This allows clients to react programmatically if appropriate.

примечание

• The server controls when the elicitation is considered completed
• The client only confirms acceptance
• Useful for payments, SSO, external confirmations

Learn By Example

A complete working example is available here.