Errors

Exceptions

Domain-specific error types raised by the MCP server and components.

`arcade_mcp_server.exceptions`

MCP Exception Hierarchy

Provides domain-specific exceptions for better error handling and debugging.

`AuthorizationError`

Bases: MCPContextError

Authorization failure.

`LifespanError`

Bases: ServerError

Error in lifespan management.

`MCPContextError`

Bases: MCPError

Error in context management.

`MCPError`

Bases: Exception

Base error for all MCP-related exceptions.

`MCPRuntimeError`

Bases: MCPError

Runtime error for all MCP-related exceptions.

`NotFoundError`

Bases: MCPContextError

Requested entity not found.

`PromptError`

Bases: MCPContextError

Error in prompt management.

`ProtocolError`

Bases: MCPRuntimeError

Error in MCP protocol handling.

`RequestError`

Bases: ServerError

Error in request processing from client to server

`ResourceError`

Bases: MCPContextError

Error in resource management.

`ResponseError`

Bases: ServerError

Error in request processing from server -> client

`ServerError`

Bases: MCPRuntimeError

Error in server operations.

`ServerRequestError`

Bases: RequestError

Error in sending request from server -> client initiated by the server

`SessionError`

Bases: ServerError

Error in session management

`TransportError`

Bases: MCPRuntimeError

Error in transport layer (stdio, HTTP, etc).

Examples

from arcade_mcp_server.exceptions import (
    MCPError,
    NotFoundError,
    DuplicateError,
    ValidationError,
    ToolError,
)

# Raising a not-found when a resource is missing
async def read_resource_or_fail(uri: str) -> str:
    if not await exists(uri):
        raise NotFoundError(f"Resource not found: {uri}")
    return await read(uri)

# Validating input
def validate_age(age: int) -> None:
    if age < 0:
        raise ValidationError("age must be non-negative")

# Handling tool execution errors in middleware or handlers
async def call_tool_safely(call):
    try:
        return await call()
    except ToolError as e:
        # Convert to an error result or re-raise
        raise MCPError(f"Tool failed: {e}")