Trait PromptHandler 

pub trait PromptHandler: Send + Sync {
    // Required methods
    fn definition(&self) -> Prompt;
    fn get(
        &self,
        ctx: &McpContext,
        arguments: HashMap<String, String>,
    ) -> McpResult<Vec<PromptMessage>>;

    // Provided methods
    fn icon(&self) -> Option<&Icon> { ... }
    fn version(&self) -> Option<&str> { ... }
    fn tags(&self) -> &[String] { ... }
    fn timeout(&self) -> Option<Duration> { ... }
    fn get_async<'a>(
        &'a self,
        ctx: &'a McpContext,
        arguments: HashMap<String, String>,
    ) -> BoxFuture<'a, McpOutcome<Vec<PromptMessage>>> { ... }
}

Handler for a prompt.

This trait is typically implemented via the #[prompt] macro.

Sync vs Async

By default, implement get() for synchronous execution. For async prompts, override get_async() instead. The router always calls get_async(), which defaults to running get() in an async block.

Return Type

Async handlers return McpOutcome<Vec<PromptMessage>>, a 4-valued type.

Required Methods

fn definition(&self) -> Prompt

Returns the prompt definition.

fn get( &self, ctx: &McpContext, arguments: HashMap<String, String>, ) -> McpResult<Vec<PromptMessage>>

Gets the prompt messages synchronously with the given arguments.

This is the default implementation point. Override this for simple synchronous prompts. Returns McpResult which is converted to McpOutcome by the async wrapper.

Provided Methods

fn icon(&self) -> Option<&Icon>

Returns the prompt’s icon, if any.

Default implementation returns None. Override to provide an icon. Note: Icons can also be set directly in definition().

fn version(&self) -> Option<&str>

Returns the prompt’s version, if any.

Default implementation returns None. Override to provide a version. Note: Version can also be set directly in definition().

fn tags(&self) -> &[String]

Returns the prompt’s tags for filtering and organization.

Default implementation returns an empty slice. Override to provide tags. Note: Tags can also be set directly in definition().

fn timeout(&self) -> Option<Duration>

Returns the prompt’s custom timeout duration.

Default implementation returns None, meaning the server’s default timeout applies. Override to specify a per-handler timeout.

fn get_async<'a>( &'a self, ctx: &'a McpContext, arguments: HashMap<String, String>, ) -> BoxFuture<'a, McpOutcome<Vec<PromptMessage>>>

Gets the prompt messages asynchronously with the given arguments.

Override this for prompts that need true async execution (e.g., template fetching, dynamic content generation).

Returns McpOutcome to properly represent all four states.

The default implementation delegates to the sync get() method.

Implementors