Struct McpMessage 

pub struct McpMessage {
    pub jsonrpc: String,
    pub id: Option<Value>,
    pub method: Option<String>,
    pub params: Option<Value>,
    pub result: Option<Value>,
    pub error: Option<JsonRpcError>,
}

A parsed MCP message (JSON-RPC 2.0 envelope).

MCP uses JSON-RPC 2.0 over stdio or HTTP. Every message is one of:

• Request: has method + params, has id
• Response: has result or error, has id
• Notification: has method + params, no id

Fields

jsonrpc: String

id: Option<Value>

Request/response correlation ID. None for notifications.

method: Option<String>

Method name (e.g. “tools/call”, “tools/list”, “initialize”).

params: Option<Value>

Method parameters.

result: Option<Value>

Success response payload.

error: Option<JsonRpcError>

Error response payload.

Implementations

impl McpMessage

pub fn parse(raw: &str) -> Result<Self, Error>

Parse a JSON-RPC message from a raw JSON string.

pub fn to_json(&self) -> Result<String, Error>

Serialize this message to a JSON string (no trailing newline).

pub fn is_request(&self) -> bool

True if this is a request (has method + id).

pub fn is_notification(&self) -> bool

True if this is a notification (has method, no id).

pub fn is_response(&self) -> bool

True if this is a response (has result or error + id).

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

If this is a tools/call request, extract the tool name.

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

If this is a resources/read request, extract the resource URI from params.uri.

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

If this is a prompts/get request, extract the prompt name from params.name.

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

Return the primary “resource identifier” being accessed for any MCP method.

• tools/call -> tool name (params.name)
• resources/read -> resource URI (params.uri)
• prompts/get -> prompt name (params.name)
• Listing methods (resources/list, tools/list, prompts/list) -> None
• All other methods -> None

pub fn error_response(id: Value, code: i64, message: impl Into<String>) -> Self

Create a JSON-RPC error response for a given request ID.

Trait Implementations

impl Clone for McpMessage

fn clone(&self) -> McpMessage

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for McpMessage

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for McpMessage

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for McpMessage

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

where __S: Serializer,

Serialize this value into the given Serde serializer.