Struct RequestMeta 

pub struct RequestMeta {
    pub progress_token: Option<ProgressToken>,
    pub protocol_version: Option<String>,
    pub client_info: Option<Implementation>,
    pub client_capabilities: Option<ClientCapabilities>,
    pub log_level: Option<LogLevel>,
}

Request metadata (_meta).

Carries the progress token (all versions) and, under 2026-07-28 (SEP-2575), the per-request protocol version, client identity, client capabilities, and log level that replaced the initialize handshake. Every 2026-07-28 key is optional here so a single type serves both protocol versions: a 2025-11-25 request carries none of them and serializes byte-identically. Use RequestMeta::validate_for_version to enforce the keys a version requires.

Fields

progress_token: Option<ProgressToken>

Progress token for receiving progress notifications.

protocol_version: Option<String>

SEP-2575: the MCP protocol version for this request. Required on 2026-07-28; on the HTTP transport it MUST match the MCP-Protocol-Version header.

client_info: Option<Implementation>

SEP-2575: self-reported client software identity. Optional.

client_capabilities: Option<ClientCapabilities>

SEP-2575: the client’s capabilities for this specific request. Required on 2026-07-28; declared per-request rather than once at initialization.

log_level: Option<LogLevel>

SEP-2575: desired log level for this request. Optional.

Deprecated as of 2026-07-28 (SEP-2577); it replaced the logging/setLevel RPC. If absent, the server MUST NOT emit notifications/message for the request.

Implementations

impl RequestMeta

pub fn validate_for_version( &self, protocol_version: &str, ) -> Result<(), MissingMetaKey>

Validate that the _meta keys the given protocol version requires are present. Under 2026-07-28 (SEP-2575), protocolVersion and clientCapabilities are required; earlier versions carry neither and always pass.

Trait Implementations

impl Clone for RequestMeta

fn clone(&self) -> RequestMeta

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for RequestMeta

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

Formats the value using the given formatter.

impl Default for RequestMeta

fn default() -> RequestMeta

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for RequestMeta

fn deserialize<__D>( __deserializer: __D, ) -> Result<RequestMeta, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for RequestMeta

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.