Enum Error 

pub enum Error {
    Connection {
        url: String,
        source: Error,
    },
    Request {
        url: String,
        source: Error,
    },
    BadStatus {
        url: String,
        code: StatusCode,
        body: String,
    },
    JsonRpc {
        url: String,
        code: i64,
        message: String,
        data: Option<Value>,
    },
    SessionExpired {
        url: String,
    },
    NoSessionId {
        url: String,
        body: String,
    },
    MissingAuthorization(String),
    MalformedResponse {
        url: String,
        message: String,
    },
}

Errors that can occur during MCP operations.

Variants

Connection

Failed to connect to the MCP server.

Fields

url: String

The URL the failing request was targeting.

source: Error

The underlying reqwest error.

Request

HTTP request failed (post-connect).

Fields

url: String

The URL the failing request was targeting.

source: Error

The underlying reqwest error.

BadStatus

Server returned a non-success HTTP status code.

Fields

url: String

The URL the failing request was targeting.

code: StatusCode

The HTTP status code received.

body: String

The response body.

JsonRpc

The server returned a JSON-RPC error.

Fields

url: String

The URL the failing request was targeting.

code: i64

The JSON-RPC error code.

message: String

The error message.

data: Option<Value>

Optional additional error data.

SessionExpired

The session expired (server returned 404).

Fields

url: String

The URL whose session was expired.

NoSessionId

The server did not return a session ID on initialization.

Fields

url: String

The URL we attempted to initialize against.

body: String

The response body the server returned, truncated to a reasonable preview length. Often carries a JSON-RPC error describing why the session wasn’t created (e.g., upstream connect failed for a specific URL).

MissingAuthorization(String)

Authorization required but not provided for this MCP server URL.

MalformedResponse

The server returned a body that wasn’t decodable as JSON or SSE.

Fields

url: String

The URL that produced the unparseable response.

message: String

What was wrong with the body, including a preview.

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.