fastmcp_rs/
error.rs

1use std::fmt;
2use std::io;
3
4use serde_json::Value;
5use thiserror::Error;
6
7/// Result alias used across the crate.
8pub type Result<T, E = FastMcpError> = std::result::Result<T, E>;
9
10/// Errors surfaced by the FastMCP Rust prototype.
11#[derive(Debug, Error)]
12pub enum FastMcpError {
13    #[error("tool '{0}' already registered")]
14    DuplicateTool(String),
15    #[error("tool '{0}' not found")]
16    ToolNotFound(String),
17    #[error("resource '{0}' already registered")]
18    DuplicateResource(String),
19    #[error("resource '{0}' not found")]
20    ResourceNotFound(String),
21    #[error("prompt '{0}' already registered")]
22    DuplicatePrompt(String),
23    #[error("prompt '{0}' not found")]
24    PromptNotFound(String),
25    #[error("invalid invocation payload: {0}")]
26    InvalidInvocation(String),
27    #[error("handler error: {0}")]
28    HandlerError(String),
29    #[error("serialization error: {0}")]
30    Serialization(#[from] serde_json::Error),
31    #[error("io error: {0}")]
32    Io(#[from] io::Error),
33}
34
35impl FastMcpError {
36    /// Convenience helper for building handler errors from any displayable type.
37    pub fn handler_error(err: impl fmt::Display) -> Self {
38        Self::HandlerError(err.to_string())
39    }
40}
41
42/// Helper for validating the presence of a JSON object.
43pub fn expect_object<'a>(
44    payload: &'a Value,
45    context: &'static str,
46) -> Result<&'a serde_json::Map<String, Value>> {
47    payload
48        .as_object()
49        .ok_or_else(|| FastMcpError::InvalidInvocation(format!("{context} expects a JSON object")))
50}
fastmcp_rs/error.rs

fastmcp_rs/
error.rs
