Enum McpErrorCode 

pub enum McpErrorCode {
    ParseError,
    InvalidRequest,
    MethodNotFound,
    InvalidParams,
    InternalError,
    ServerError(i32),
    Unknown(i32),
}

MCP JSON-RPC error codes per MCP specification.

These error codes follow the JSON-RPC 2.0 specification and are preserved from rmcp errors for better debugging and error handling.

Error Code Ranges

• -32700: Parse error (invalid JSON)
• -32600: Invalid request
• -32601: Method not found
• -32602: Invalid params
• -32603: Internal error
• -32000 to -32099: Server errors (implementation-defined)

Example

use nika_mcp::McpErrorCode;

let code = McpErrorCode::from_code(-32602);
assert_eq!(code, McpErrorCode::InvalidParams);
assert!(code.is_client_error());

Variants

ParseError

Parse error: Invalid JSON was received by the server (-32700)

InvalidRequest

Invalid request: The JSON sent is not a valid Request object (-32600)

MethodNotFound

Method not found: The method does not exist / is not available (-32601)

InvalidParams

Invalid params: Invalid method parameter(s) (-32602)

InternalError

Internal error: Internal JSON-RPC error (-32603)

ServerError(i32)

Server error: Implementation-defined server errors (-32000 to -32099)

Unknown(i32)

Unknown error code (not in JSON-RPC spec)

Implementations

impl McpErrorCode

pub fn from_code(code: i32) -> McpErrorCode

Create an error code from a numeric JSON-RPC error code.

pub fn code(&self) -> i32

Get the numeric error code.

pub fn is_client_error(&self) -> bool

Check if this is a client-side error (invalid request/params).

pub fn is_server_error(&self) -> bool

Check if this is a server-side error.

pub fn description(&self) -> &'static str

Get a human-readable description of the error code.

pub fn is_retryable(&self) -> bool

Check if this error is potentially recoverable through retry.

Returns true for transient errors that might succeed on retry:

• Internal errors (might be temporary server issues)
• Server errors (implementation-defined, often transient)

Returns false for client errors that require fixing the request:

• Parse errors (invalid JSON won’t become valid)
• Invalid request (malformed request structure)
• Invalid params (wrong parameters)
• Method not found (method doesn’t exist)

Trait Implementations

impl Clone for McpErrorCode

fn clone(&self) -> McpErrorCode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for McpErrorCode

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for McpErrorCode

fn deserialize<__D>( __deserializer: __D, ) -> Result<McpErrorCode, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for McpErrorCode

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

Formats the value using the given formatter.

impl From<i32> for McpErrorCode

fn from(code: i32) -> McpErrorCode

Converts to this type from the input type.

impl Hash for McpErrorCode

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for McpErrorCode

fn eq(&self, other: &McpErrorCode) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for McpErrorCode

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for McpErrorCode

impl Eq for McpErrorCode

impl StructuralPartialEq for McpErrorCode