Enum McpError 

pub enum McpError {
    VersionMismatch {
        expected: String,
        actual: String,
    },
    InvalidCapability(String),
    ToolNotFound(String),
    ResourceNotFound(String),
    PromptNotFound(String),
    InvalidRequest {
        message: String,
    },
    InvalidParameters(String),
    MissingParameter(String),
    InvalidParameterType {
        param: String,
        expected: String,
        actual: String,
    },
    ParameterOutOfRange {
        param: String,
        value: String,
        constraint: String,
    },
    ToolExecutionError(String),
    ResourceExecutionError(String),
    PromptExecutionError(String),
    ResourceAccessDenied(String),
    ConfigurationError(String),
    SessionError(String),
    ValidationError(String),
    IoError(Error),
    SerializationError(Error),
    TransportError(String),
    JsonRpcProtocolError(String),
    JsonRpcError {
        code: i64,
        message: String,
        data: Option<Value>,
    },
}

MCP-specific errors

Variants

VersionMismatch

Fields

expected: String

actual: String

InvalidCapability(String)

ToolNotFound(String)

ResourceNotFound(String)

PromptNotFound(String)

InvalidRequest

Fields

message: String

InvalidParameters(String)

MissingParameter(String)

InvalidParameterType

Fields

param: String

expected: String

actual: String

ParameterOutOfRange

Fields

param: String

value: String

constraint: String

ToolExecutionError(String)

ResourceExecutionError(String)

PromptExecutionError(String)

ResourceAccessDenied(String)

ConfigurationError(String)

SessionError(String)

ValidationError(String)

IoError(Error)

SerializationError(Error)

TransportError(String)

JsonRpcProtocolError(String)

JsonRpcError

A JSON-RPC error with preserved code, message, and optional data.

Used by tasks/result to reproduce the original error verbatim, as required by the MCP spec: “tasks/result MUST return that same JSON-RPC error.”

Fields

code: i64

message: String

data: Option<Value>

Implementations

impl McpError

pub fn missing_param(param: &str) -> McpError

Create a missing parameter error

pub fn invalid_param_type(param: &str, expected: &str, actual: &str) -> McpError

Create an invalid parameter type error

pub fn param_out_of_range( param: &str, value: &str, constraint: &str, ) -> McpError

Create a parameter out of range error

pub fn tool_execution(message: &str) -> McpError

Create a tool execution error

pub fn resource_execution(message: &str) -> McpError

Create a resource execution error

pub fn prompt_execution(message: &str) -> McpError

Create a prompt execution error

pub fn validation(message: &str) -> McpError

Create a validation error

pub fn configuration(message: &str) -> McpError

Create a configuration error

pub fn transport(message: &str) -> McpError

Create a transport error

pub fn json_rpc_protocol(message: &str) -> McpError

Create a JSON-RPC protocol error

pub fn json_rpc_error( code: i64, message: impl Into<String>, data: Option<Value>, ) -> McpError

Create a JSON-RPC error with preserved code, message, and optional data.

Used by tasks/result to reproduce original errors verbatim.

pub fn to_error_object(&self) -> JsonRpcErrorObject

Convert to a JsonRpcErrorObject for JSON-RPC 2.0 responses

pub fn to_json_rpc_response(&self, id: Option<RequestId>) -> JsonRpcError

Create a JSON-RPC error response for this MCP error

pub fn to_json_rpc_error(&self) -> JsonRpcErrorObject

👎Deprecated:

Use to_error_object() instead for cleaner architecture

Legacy method for backward compatibility - use to_error_object() instead

Trait Implementations

impl Debug for McpError

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

Formats the value using the given formatter.

impl Display for McpError

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

Formats the value using the given formatter.

impl Error for McpError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<&str> for McpError

fn from(message: &str) -> McpError

Converts to this type from the input type.

impl From<Error> for McpError

fn from(source: Error) -> McpError

Converts to this type from the input type.

impl From<Error> for McpError

fn from(source: Error) -> McpError

Converts to this type from the input type.

impl From<String> for McpError

fn from(message: String) -> McpError

Converts to this type from the input type.

impl ToJsonRpcError for McpError

fn to_error_object(&self) -> JsonRpcErrorObject

Convert this error to a JSON-RPC error object