Enum Error 

pub enum Error {
    JsonRpc(JsonRpcError),
    Serialization(Error),
    Tool(ToolError),
    Transport(String),
    Internal(String),
}

tower-mcp error type

Variants

JsonRpc(JsonRpcError)

Serialization(Error)

Tool(ToolError)

A tool execution error.

When returned from a tool handler, this variant is mapped to JSON-RPC error code -32603 (Internal Error) in the router’s Service::call implementation. The ToolError message becomes the JSON-RPC error message.

Transport(String)

Internal(String)

Implementations

impl Error

pub fn tool(message: impl Into<String>) -> Self

Create a simple tool error from a string (for backwards compatibility)

pub fn tool_with_name( tool: impl Into<String>, message: impl Into<String>, ) -> Self

Create a tool error with the tool name

pub fn tool_from<E: Display>(err: E) -> Self

Create a tool error from any Display type.

This is useful for converting errors in a map_err chain:

let result: Result<(), std::io::Error> = Err(std::io::Error::other("oops"));
result.map_err(Error::tool_from)?;

pub fn tool_context<E: Display>(context: impl Into<String>, err: E) -> Self

Create a tool error with context prefix.

This is useful for adding context when converting errors:

let result: Result<(), std::io::Error> = Err(std::io::Error::other("connection refused"));
result.map_err(|e| Error::tool_context("API request failed", e))?;

pub fn invalid_params(message: impl Into<String>) -> Self

Create a JSON-RPC “Invalid params” error (-32602).

Shorthand for Error::JsonRpc(JsonRpcError::invalid_params(msg)).

let err = Error::invalid_params("missing required field 'name'");

pub fn internal(message: impl Into<String>) -> Self

Create a JSON-RPC “Internal error” error (-32603).

Shorthand for Error::JsonRpc(JsonRpcError::internal_error(msg)).

let err = Error::internal("unexpected state");

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

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<Error> for Error

fn from(source: Error) -> Self

Converts to this type from the input type.

impl From<JsonRpcError> for Error

fn from(err: JsonRpcError) -> Self

Converts to this type from the input type.

impl From<ToolError> for Error

fn from(source: ToolError) -> Self

Converts to this type from the input type.