Attribute Macro mcp_tool 

#[mcp_tool]

Available on crate feature macros only.

Marks a method as an MCP tool.

Note: This is an inert marker attribute that should only be used within impl blocks marked with #[mcp_server]. When used outside of #[mcp_server], it will generate tool metadata but won’t be collected into a server.

Example

#[mcp_server]
impl MyServer {
    #[mcp_tool(description = "Store a value in memory")]
    pub fn memory_write(
        &self,
        #[mcp(description = "The scope/namespace")]
        scope: String,
        #[mcp(description = "The key to store under")]
        key: String,
    ) -> Result<String, String> {
        // implementation
    }
}