Enum McpError 

#[non_exhaustive]
pub enum McpError {
    Transport(String),
    Protocol(String),
    Command {
        command: String,
        message: String,
    },
}

Failure modes for the crate::McpServer runtime.

Clone is derived so callers can route errors through retry pipelines or attach them to telemetry events without losing the underlying detail. The variants intentionally hold owned String payloads — the rmcp and std::io errors that surface here are already stringified at the boundary.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Transport(String)

A transport-level failure: bind, accept, or socket error. Surfaced from rmcp’s transport layer.

Protocol(String)

An MCP protocol violation we surfaced. Most protocol errors are handled by rmcp itself — this variant covers the cases rtb-mcp raises (unknown tool name, invalid arguments).

Command

A registered rtb_app::command::Command::run returned an error during a tools/call invocation. The error is forwarded to the MCP client as the call’s is_error: true payload.

Fields

command: String

Tool name as advertised in list_tools.

message: String

Stringified failure message from the underlying command.

Trait Implementations

impl Clone for McpError

fn clone(&self) -> McpError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for McpError

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

Formats the value using the given formatter.

impl Diagnostic for McpError

fn code(&self) -> Option<Box<dyn Display + '_>>

Unique diagnostic code that can be used to look up more information about this Diagnostic. Ideally also globally unique, and documented in the toplevel crate’s documentation for easy searching. Rust path format (foo::bar::baz) is recommended, but more classic codes like E0123 or enums will work just fine.

fn severity(&self) -> Option<Severity>

Diagnostic severity. This may be used by ReportHandlers to change the display format of this diagnostic.

fn help<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

Additional help text related to this Diagnostic. Do you have any advice for the poor soul who’s just run into this issue?

fn url<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

URL to visit for a more detailed explanation/help about this Diagnostic.

fn source_code(&self) -> Option<&dyn SourceCode>

Source code to apply this Diagnostic’s Diagnostic::labels to.

fn labels(&self) -> Option<Box<dyn Iterator<Item = LabeledSpan> + '_>>

Labels to apply to this Diagnostic’s Diagnostic::source_code

fn related<'a>( &'a self, ) -> Option<Box<dyn Iterator<Item = &'a dyn Diagnostic> + 'a>>

Additional related Diagnostics.

fn diagnostic_source(&self) -> Option<&dyn Diagnostic>

The cause of the error.

impl Display for McpError

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

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.