Struct Context 

pub struct Context<'a> {
    pub request_id: &'a RequestId,
    pub progress_token: Option<&'a ProgressToken>,
    pub client_caps: &'a ClientCapabilities,
    pub server_caps: &'a ServerCapabilities,
    pub protocol_version: ProtocolVersion,
    /* private fields */
}

Request context passed to handler methods.

The context uses lifetime references to avoid 'static requirements and Arc overhead. This enables:

• Single-threaded async without Arc overhead
• !Send types in handlers (important for some runtimes)
• Users who need spawning can wrap in Arc themselves

Per the plan: “Request context - passed by reference, NO ’static requirement”

Fields

request_id: &'a RequestId

The request ID for this operation.

progress_token: Option<&'a ProgressToken>

Optional progress token for reporting progress.

client_caps: &'a ClientCapabilities

Client capabilities negotiated during initialization.

server_caps: &'a ServerCapabilities

Server capabilities advertised during initialization.

protocol_version: ProtocolVersion

The negotiated protocol version.

Use this to check version-specific feature availability via methods like supports_tasks(), supports_elicitation(), etc.

Implementations

impl<'a> Context<'a>

pub fn new( request_id: &'a RequestId, progress_token: Option<&'a ProgressToken>, client_caps: &'a ClientCapabilities, server_caps: &'a ServerCapabilities, protocol_version: ProtocolVersion, peer: &'a dyn Peer, ) -> Self

Create a new context with all required references.

pub fn with_cancellation( request_id: &'a RequestId, progress_token: Option<&'a ProgressToken>, client_caps: &'a ClientCapabilities, server_caps: &'a ServerCapabilities, protocol_version: ProtocolVersion, peer: &'a dyn Peer, cancel: CancellationToken, ) -> Self

Create a new context with a custom cancellation token.

pub fn is_cancelled(&self) -> bool

Check if the request has been cancelled.

pub fn cancelled(&self) -> impl Future<Output = ()> + '_

Get a future that completes when the request is cancelled.

pub const fn cancellation_token(&self) -> &CancellationToken

Get the cancellation token for this context.

pub async fn notify( &self, method: &str, params: Option<Value>, ) -> Result<(), McpError>

Send a notification to the client.

Arguments

• method - The notification method name
• params - Optional notification parameters

Errors

Returns an error if the notification could not be sent.

pub async fn progress( &self, current: u64, total: Option<u64>, message: Option<&str>, ) -> Result<(), McpError>

Report progress for this operation.

This sends a progress notification to the client if a progress token was provided with the request.

Arguments

• current - Current progress value
• total - Total progress value (if known)
• message - Optional progress message

Errors

Returns an error if the notification could not be sent.

Trait Implementations

impl Debug for Context<'_>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.