tool-handler.class.ts•3.32 kB
import { getLogger } from "../logging";
import type { Logger } from "../logging";
/**
* ToolHandler - Base implementation for MCP tool handlers
*
* This provides a standardized foundation for implementing MCP tool handlers
* with consistent error handling, logging, and response formatting.
*/
import {
type McpResponse,
createErrorResponse,
createSuccessResponse,
} from "../responses";
// Use existing validation utilities if needed
import type { Tool, ToolHandler } from "./tool.interface";
/**
* Base class for MCP tool handlers
* Provides essential functionality for all tool handlers
*/
export abstract class BaseToolHandler<TParams = unknown, TResult = unknown>
implements ToolHandler<TParams>, Tool
{
/**
* Logger instance for this tool handler
*/
protected readonly logger: Logger;
/**
* Defines the name of this tool
*/
public readonly name: string;
/**
* Defines the feature this tool belongs to
*/
public readonly feature: string;
/**
* Initialize the tool handler with name
*
* @param feature - The name of the feature this tool handler belongs to
* @param name - The name of this specific tool
* @param description - Optional description of what the tool does
*/
constructor(
feature: string,
name: string,
public readonly description?: string,
) {
this.feature = feature;
this.name = name;
this.logger = getLogger(`${feature}:${name}`);
this.logger.debug("Tool handler initialized");
}
/**
* Execute tool-specific logic
* This is the main method that subclasses must implement
*/
protected abstract execute(params: TParams): Promise<TResult> | TResult;
/**
* Format the result for MCP response
* Default implementation handles strings and objects
*/
protected formatResult(result: TResult): McpResponse {
if (typeof result === "string") {
return createSuccessResponse(result);
}
return createSuccessResponse(
typeof result === "object" ? result : String(result),
);
}
/**
* Standard handler implementation with error handling
*
* @param params - The parameters for the tool request
* @returns The formatted MCP response
*/
public handle(params: unknown): Promise<McpResponse> | McpResponse {
try {
this.logger.debug("Tool execution started");
// Type casting here as subclasses will handle validation
const result = this.execute(params as TParams);
if (result instanceof Promise) {
return result
.then((resolvedResult) => {
this.logger.debug("Tool execution completed successfully");
return this.formatResult(resolvedResult);
})
.catch((error) => {
this.logger.error("Tool execution failed", {
prefix: String(error),
});
return createErrorResponse(
error instanceof Error ? error.message : String(error),
);
});
}
this.logger.debug("Tool execution completed successfully");
return this.formatResult(result);
} catch (error) {
this.logger.error("Tool execution failed", { prefix: String(error) });
return createErrorResponse(
error instanceof Error ? error.message : String(error),
);
}
}
}