Struct McpRequestMetadata 

pub struct McpRequestMetadata(pub MetaObject);

The official SDK’s typed stable per-request metadata map. The _meta map carried by requests (spec RequestMetaObject).

In addition to arbitrary extension keys, requests reserve:

• progressToken for progress tracking
• io.modelcontextprotocol/protocolVersion (SEP-2575)
• io.modelcontextprotocol/clientInfo (SEP-2575)
• io.modelcontextprotocol/clientCapabilities (SEP-2575)
• io.modelcontextprotocol/logLevel (SEP-2575)

The 2026-07-28 draft schema requires the protocol-version and client-capabilities keys; client-info is optional. Earlier protocol versions do not know them. All keys therefore stay optional at runtime and in the generated (version-shared) JSON schema — use RequestMetaObject::missing_required_keys to validate a request against the negotiated protocol version.

This type dereferences to MetaObject (and transitively to the underlying map), so general helpers such as the SEP-414 trace-context accessors remain available.

Tuple Fields

0: MetaObject

Implementations

impl RequestMetaObject

pub const DRAFT_REQUIRED_KEYS: [&'static str; 2]

Request _meta keys the 2026-07-28 draft schema marks as required.

pub fn new() -> RequestMetaObject

Create an empty request metadata map.

pub fn with_progress_token(token: ProgressToken) -> RequestMetaObject

Create a new request meta with a progress token set

pub fn with_client_context( protocol_version: ProtocolVersion, client_info: Implementation, client_capabilities: ClientCapabilities, ) -> RequestMetaObject

Create request metadata with the client context SEP-2575 requires on every request.

pub fn get_progress_token(&self) -> Option<ProgressToken>

Get the progress token carried in _meta, if present and valid.

pub fn set_progress_token(&mut self, token: ProgressToken)

Set the progress token carried in _meta.

pub fn protocol_version(&self) -> Option<ProtocolVersion>

Get the MCP protocol version carried in _meta, if present and valid.

pub fn set_protocol_version(&mut self, protocol_version: ProtocolVersion)

Set the MCP protocol version carried in _meta.

pub fn client_info(&self) -> Option<Implementation>

Get the client implementation identity carried in _meta, if present and valid.

pub fn set_client_info(&mut self, client_info: Implementation)

Set the client implementation identity carried in _meta.

pub fn client_capabilities(&self) -> Option<ClientCapabilities>

Get the client capabilities carried in _meta, if present and valid.

pub fn set_client_capabilities( &mut self, client_capabilities: ClientCapabilities, )

Set the client capabilities carried in _meta.

pub fn log_level(&self) -> Option<LoggingLevel>

Get the requested per-request log level carried in _meta, if present and valid.

pub fn set_log_level(&mut self, log_level: LoggingLevel)

Set the requested per-request log level carried in _meta.

pub fn missing_required_keys( &self, protocol_version: &ProtocolVersion, ) -> Vec<&'static str>

Return the Self::DRAFT_REQUIRED_KEYS whose values are absent or invalid in this map, if protocol_version requires them.

A key counts as missing when it is not present or when its value does not decode into the expected type (e.g. a numeric protocolVersion or a string clientInfo), matching what the typed accessors return.

Protocol versions before 2026-07-28 have no required request metadata, so this always returns an empty list for them.

Examples

use rmcp::model::{ProtocolVersion, RequestMetaObject};

let meta = RequestMetaObject::new();
// Older protocols have no required request metadata.
assert!(
    meta.missing_required_keys(&ProtocolVersion::V_2025_11_25)
        .is_empty()
);
// The 2026-07-28 protocol requires per-request context.
assert_eq!(
    meta.missing_required_keys(&ProtocolVersion::V_2026_07_28),
    RequestMetaObject::DRAFT_REQUIRED_KEYS.to_vec(),
);

pub fn extend(&mut self, other: RequestMetaObject)

Insert every entry of other, overwriting existing keys on conflict.

Methods from Deref<Target = MetaObject>

pub fn get_traceparent(&self) -> Option<&str>

Get the W3C traceparent value (SEP-414), if present.

pub fn set_traceparent(&mut self, value: impl Into<String>)

Set the W3C traceparent value (SEP-414).

use rmcp::model::MetaObject;

let mut meta = MetaObject::new();
meta.set_traceparent("00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01");
assert_eq!(
    meta.get_traceparent(),
    Some("00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01"),
);

pub fn get_tracestate(&self) -> Option<&str>

Get the W3C tracestate value (SEP-414), if present.

pub fn set_tracestate(&mut self, value: impl Into<String>)

Set the W3C tracestate value (SEP-414).

pub fn get_baggage(&self) -> Option<&str>

Get the W3C baggage value (SEP-414), if present.

pub fn set_baggage(&mut self, value: impl Into<String>)

Set the W3C baggage value (SEP-414).

pub fn extend(&mut self, other: MetaObject)

Insert every entry of other, overwriting existing keys on conflict.

Methods from Deref<Target = Map<String, Value>>

pub fn get<Q>(&self, key: &Q) -> Option<&Value>

where String: Borrow<Q>, Q: Ord + Eq + Hash + ?Sized,

Returns a reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn contains_key<Q>(&self, key: &Q) -> bool

where String: Borrow<Q>, Q: Ord + Eq + Hash + ?Sized,

Returns true if the map contains a value for the specified key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn get_key_value<Q>(&self, key: &Q) -> Option<(&String, &Value)>

where String: Borrow<Q>, Q: Ord + Eq + Hash + ?Sized,

Returns the key-value pair matching the given key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn len(&self) -> usize

Returns the number of elements in the map.

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

pub fn iter(&self) -> Iter<'_>

Gets an iterator over the entries of the map.

pub fn keys(&self) -> Keys<'_>

Gets an iterator over the keys of the map.

pub fn values(&self) -> Values<'_>

Gets an iterator over the values of the map.

Trait Implementations

impl Clone for RequestMetaObject

fn clone(&self) -> RequestMetaObject

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for RequestMetaObject

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

Formats the value using the given formatter.

impl Default for RequestMetaObject

fn default() -> RequestMetaObject

Returns the “default value” for a type.

impl Deref for RequestMetaObject

type Target = MetaObject

The resulting type after dereferencing.

fn deref(&self) -> &<RequestMetaObject as Deref>::Target

Dereferences the value.

impl DerefMut for RequestMetaObject

fn deref_mut(&mut self) -> &mut <RequestMetaObject as Deref>::Target

Mutably dereferences the value.

impl<'de> Deserialize<'de> for RequestMetaObject

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<Map<String, Value>> for RequestMetaObject

fn from(object: Map<String, Value>) -> RequestMetaObject

Converts to this type from the input type.

impl From<MetaObject> for RequestMetaObject

fn from(meta: MetaObject) -> RequestMetaObject

Converts to this type from the input type.

impl PartialEq for RequestMetaObject

fn eq(&self, other: &RequestMetaObject) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for RequestMetaObject

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.

impl StructuralPartialEq for RequestMetaObject