Struct ProtocolVersionConfig 

pub struct ProtocolVersionConfig {
    pub preferred: String,
    pub supported: Vec<String>,
    pub allow_fallback: bool,
}

Protocol version configuration for MCP version negotiation

Version Negotiation Behavior

When a client connects, the server negotiates protocol version as follows:

1. If client requests a version in supported list → use client’s version
2. If allow_fallback is true and client’s version not supported → offer preferred
3. If allow_fallback is false → reject connection if versions don’t match

Examples

use turbomcp_server::ProtocolVersionConfig;

// Default: Latest spec with fallback enabled
let config = ProtocolVersionConfig::default();

// Strict: Only accept latest spec, no fallback
let config = ProtocolVersionConfig::strict("2025-11-25");

// Compatible: Prefer older version for maximum compatibility
let config = ProtocolVersionConfig::compatible();

Fields

preferred: String

Preferred protocol version (default: “2025-11-25” - latest official spec)

supported: Vec<String>

Supported versions in fallback order (first = most preferred) Server will accept any of these versions from clients

allow_fallback: bool

Allow fallback negotiation when client requests unsupported version

• true: Offer preferred version as fallback (client can accept or disconnect)
• false: Reject connection immediately if client version not in supported list

Implementations

impl ProtocolVersionConfig

pub fn latest() -> Self

Create config with latest spec as preferred, fallback enabled

pub fn compatible() -> Self

Create config optimized for Claude Code compatibility Prefers 2025-06-18 but supports all versions

pub fn strict(version: impl Into<String>) -> Self

Create strict config - only accept the specified version, no fallback

pub fn custom( preferred: impl Into<String>, supported: Vec<impl Into<String>>, ) -> Self

Create custom config with specified versions

Trait Implementations

impl Clone for ProtocolVersionConfig

fn clone(&self) -> ProtocolVersionConfig

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ProtocolVersionConfig

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

Formats the value using the given formatter.

impl Default for ProtocolVersionConfig

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ProtocolVersionConfig

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ProtocolVersionConfig

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

where __S: Serializer,

Serialize this value into the given Serde serializer.