Enum ProtocolVersion 

pub enum ProtocolVersion {
    V2025_06_18,
    V2025_11_25,
    Draft,
    Unknown(String),
}

MCP protocol version.

Represents a known or unknown MCP specification version. Known versions get first-class enum variants; unknown version strings are preserved via Unknown for forward compatibility (e.g. proxies and protocol analyzers that handle arbitrary versions).

Ordering

Known versions are ordered by specification release date. Unknown sorts after all known versions.

Serialization

Serializes to/from the canonical version string (e.g. "2025-11-25").

Variants

V2025_06_18

MCP specification 2025-06-18

V2025_11_25

MCP specification 2025-11-25 (current stable)

Draft

Draft specification (DRAFT-2026-v1)

Unknown(String)

Unknown/future protocol version (preserved for forward compatibility)

Implementations

impl ProtocolVersion

pub const LATEST: ProtocolVersion = Self::V2025_11_25

The latest stable protocol version.

pub const STABLE: &'static [ProtocolVersion]

All stable (released) protocol versions, oldest to newest. Does not include Draft or Unknown.

pub fn as_str(&self) -> &str

The canonical version string for this protocol version.

pub fn is_known(&self) -> bool

Whether this is a named (non-Unknown) protocol version. Returns true for all variants except Unknown.

pub fn is_stable(&self) -> bool

Whether this is a stable (released) protocol version. Returns false for Draft and Unknown.

pub fn is_draft(&self) -> bool

Whether this is the draft specification.

Trait Implementations

impl Clone for ProtocolVersion

fn clone(&self) -> ProtocolVersion

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ProtocolVersion

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

Formats the value using the given formatter.

impl Default for ProtocolVersion

fn default() -> ProtocolVersion

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ProtocolVersion

fn deserialize<D>( deserializer: D, ) -> Result<ProtocolVersion, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for ProtocolVersion

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

Formats the value using the given formatter.

impl From<&str> for ProtocolVersion

fn from(s: &str) -> ProtocolVersion

Converts to this type from the input type.

impl From<String> for ProtocolVersion

fn from(s: String) -> ProtocolVersion

Converts to this type from the input type.

impl Hash for ProtocolVersion

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for ProtocolVersion

fn cmp(&self, other: &ProtocolVersion) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq<&str> for ProtocolVersion

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialEq<ProtocolVersion> for &str

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialEq for ProtocolVersion

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for ProtocolVersion

fn partial_cmp(&self, other: &ProtocolVersion) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Serialize for ProtocolVersion

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 Eq for ProtocolVersion

impl StructuralPartialEq for ProtocolVersion