Reduce boilerplate: derive/default ServerHandler for simple tool servers #711
Description
Is your feature request related to a problem? Please describe.
Problem
Building a minimal stateless tool server requires a ServerHandler
implementation that contains no real logic — just static metadata:
#[tool_handler]
impl ServerHandler for TimeServer {
fn get_info(&self) -> ServerInfo {
ServerInfo {
protocol_version: ProtocolVersion::V_2025_03_26,
capabilities: ServerCapabilities::builder().enable_tools().build(),
server_info: Implementation::new("time-server", "0.1.0"),
instructions: None,
}
}
}Describe the solution you'd like
Option A — attribute macro on the impl block:
#[tool_router]
#[mcp(name = "time-server", version = "0.1.0")]
impl TimeServer {
#[tool(description = "Get current time")]
async fn get_time(&self) -> Result<CallToolResult, McpError> { ... }
}
// No ServerHandler impl neededDescribe alternatives you've considered
Option B — derive macro with Cargo.toml defaults (like clap):
#[derive(McpServer)]
struct TimeServer;Option C — provide a default get_info() that reads
env!("CARGO_PKG_NAME") and env!("CARGO_PKG_VERSION").
Additional context
Any of these would reduce the minimal server to just
the struct + tool definitions.
Quarkus MCP (Java) requires only annotated methods — no boilerplate:
That's the entire server. No handler trait, no capabilities declaration,
no server info struct. The framework infers everything:
* Name/version from project metadata
* Capabilities from which annotations are present
* Protocol version from the library version
public class PlantUmlTool {
@Tool(description = "Renders a PlantUML string into a SVG image.")
public ImageContent renderDiagram(
@ToolArg(
description = "The PlantUML source code (starting with @startuml and ending with @enduml)."
) String source
) throws Exception {
// removed code
return new ImageContent(base64Image, "image/svg+xml");
}
}