MCP Calculator Service

const express = require("express"); const bodyParser = require("body-parser"); const cors = require("cors"); const axios = require("axios"); const { Anthropic } = require("@anthropic-ai/sdk"); const { CloudWatchLogsClient, FilterLogEventsCommand, DescribeLogGroupsCommand, } = require("@aws-sdk/client-cloudwatch-logs"); require("dotenv").config(); const app = express(); // Middleware app.use(cors()); app.use(bodyParser.json()); // Initialize Anthropic client const anthropic = new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY, }); // Initialize AWS CloudWatch Logs client const cloudWatchLogsClient = new CloudWatchLogsClient({ region: process.env.AWS_REGION || "us-east-1", credentials: { accessKeyId: process.env.AWS_ACCESS_KEY_ID, secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY, }, }); // Configuration const CALCULATOR_API_URL = process.env.CALCULATOR_API_URL || "http://localhost:3000"; // Tool definitions const tools = [ { id: "add", name: "addition", description: "Adds two numbers together", parameters: { type: "object", properties: { num1: { type: "number", description: "First number to add" }, num2: { type: "number", description: "Second number to add" }, }, required: ["num1", "num2"], }, }, { id: "subtract", name: "subtraction", description: "Subtracts second number from first number", parameters: { type: "object", properties: { num1: { type: "number", description: "Number to subtract from" }, num2: { type: "number", description: "Number to subtract" }, }, required: ["num1", "num2"], }, }, { id: "multiply", name: "multiplication", description: "Multiplies two numbers together", parameters: { type: "object", properties: { num1: { type: "number" }, num2: { type: "number" }, }, required: ["num1", "num2"], }, }, { id: "divide", name: "division", description: "Divides first number by second number", parameters: { type: "object", properties: { num1: { type: "number", description: "Number to divide" }, num2: { type: "number", description: "Number to divide by" }, }, required: ["num1", "num2"], }, }, { id: "power", name: "power", description: "Raises first number to the power of second number", parameters: { type: "object", properties: { num1: { type: "number", description: "Base number" }, num2: { type: "number", description: "Exponent" }, }, required: ["num1", "num2"], }, }, { id: "scan_logs", name: "cloudwatch_logs", description: "Scans AWS CloudWatch logs for specific string patterns", parameters: { type: "object", properties: { logGroupName: { type: "string", description: "Name of the CloudWatch log group", }, searchString: { type: "string", description: "String pattern to search for in logs", }, startTime: { type: "number", description: "Start time in milliseconds since epoch", }, endTime: { type: "number", description: "End time in milliseconds since epoch", }, }, required: ["logGroupName", "searchString"], }, }, ]; // System prompt for Claude const SYSTEM_PROMPT = `You are an AI assistant that helps users perform calculations and other mathematical tasks by selecting the appropriate tool for the job. You have access to the following tools: 1. **Addition (add)**: Adds two numbers together. 2. **Subtraction (subtract)**: Subtracts the second number from the first number. 3. **Multiplication (multiply)**: Multiplies two numbers together. 4. **Division (divide)**: Divides the first number (dividend) by the second number (divisor). 5. **Power (power)**: Raises the first number (base) to the power of the second number (exponent). 6. **CloudWatch Logs (scan_logs)**: Searches AWS CloudWatch logs for specific string patterns. When a user asks for a calculation: - Determine the correct tool to use. - Extract the necessary parameters following the exact names: - For subtraction: **num1** is the number being subtracted from, **num2** is the number being subtracted. - For division: **num1** is the dividend (number being divided), **num2** is the divisor (number to divide by). - For power: **num1** is the base, **num2** is the exponent. - For CloudWatch logs: **logGroupName** is the name of the log group, **searchString** is the pattern to search for. For complex expressions, break them into steps by adhering to the BODMAS rules: 1. **Brackets** 2. **Orders (Powers)** 3. **Division** 4. **Multiplication** 5. **Addition** 6. **Subtraction** ### Response Format Always respond in JSON format with the following structure: { "tool": "add" | "subtract" | "multiply" | "divide" | "power" | "scan_logs", "parameters": { "num1": number, "num2": number } | { "logGroupName": string, "searchString": string, "startTime"?: number, "endTime"?: number }, "explanation": "Brief explanation of what you're doing" }`; // Process user message with Claude async function processUserMessage(message) { try { const response = await anthropic.messages.create({ model: "claude-3-7-sonnet-20250219", max_tokens: 1000, system: SYSTEM_PROMPT, messages: [{ role: "user", content: message }], temperature: 0.7, }); console.log("response", JSON.stringify(response)); const content = response.content[0].text; try { // First try to find JSON in markdown code blocks const jsonMatch = content.match(/```json\n([\s\S]*?)\n```/); if (jsonMatch) { const parsedResponse = JSON.parse(jsonMatch[1].trim()); return validateAndReturnResponse(parsedResponse); } // If no markdown code block, try to find any JSON object in the text const jsonObjectMatch = content.match(/\{[\s\S]*\}/); if (jsonObjectMatch) { const parsedResponse = JSON.parse(jsonObjectMatch[0].trim()); return validateAndReturnResponse(parsedResponse); } throw new Error("No valid JSON found in response"); } catch (e) { console.error("Error parsing Claude response:", e); return { error: "Failed to parse Claude response", rawResponse: content, }; } } catch (error) { console.error("Error calling Claude:", error); throw error; } } // Helper function to validate and return the response function validateAndReturnResponse(parsedResponse) { // Validate the response structure if ( !parsedResponse.tool || !parsedResponse.parameters || !parsedResponse.explanation ) { throw new Error("Invalid response structure"); } // Validate parameters based on tool type if (parsedResponse.tool === "scan_logs") { if ( typeof parsedResponse.parameters.logGroupName !== "string" || typeof parsedResponse.parameters.searchString !== "string" ) { throw new Error("Invalid parameter types for scan_logs"); } } else { // Validate calculator parameters if ( typeof parsedResponse.parameters.num1 !== "number" || typeof parsedResponse.parameters.num2 !== "number" ) { throw new Error("Invalid parameter types for calculator operations"); } } return parsedResponse; } // Endpoint for tool discovery app.get("/tools", (req, res) => { res.json(tools); }); // Endpoint for tool execution app.post("/execute/:toolId", async (req, res) => { const { toolId } = req.params; const params = req.body; console.log(`Executing tool: ${toolId} with params:`, params); try { if (!tools.find((t) => t.id === toolId)) { return res.status(404).json({ error: `Tool '${toolId}' not found` }); } if (toolId === "scan_logs") { const command = new FilterLogEventsCommand({ logGroupName: params.logGroupName, filterPattern: params.searchString, startTime: params.startTime, endTime: params.endTime, }); const response = await cloudWatchLogsClient.send(command); return res.json({ events: response.events, nextToken: response.nextToken, }); } const response = await axios.post( `${CALCULATOR_API_URL}/${toolId}`, params ); return res.json(response.data); } catch (error) { console.error(`Error executing tool ${toolId}:`, error.message); if (error.response) { return res.status(error.response.status).json(error.response.data); } return res.status(500).json({ error: "Internal server error" }); } }); // LLM agent interface endpoint app.post("/agent", async (req, res) => { const { message } = req.body; if (!message) { return res.status(400).json({ error: "Message is required" }); } try { const claudeResponse = await processUserMessage(message); if (claudeResponse.error) { return res.status(500).json({ error: claudeResponse.error }); } const { tool, parameters, explanation } = claudeResponse; let result; if (tool === "scan_logs") { try { // Special case: Listing all log groups if ( parameters.logGroupName === "/" || parameters.logGroupName === "*" ) { const allLogGroups = await cloudWatchLogsClient.send( new DescribeLogGroupsCommand({}) ); return res.json({ explanation: "Listing all available AWS CloudWatch log groups", result: { logGroups: allLogGroups.logGroups?.map((group) => ({ name: group.logGroupName, lastEventTime: group.lastEventTimestamp, creationTime: group.creationTime, retentionInDays: group.retentionInDays, })) || [], }, toolUsed: "list_log_groups", }); } // Normal case: Searching within a specific log group const logGroupName = parameters.logGroupName.startsWith("/aws/lambda/") ? parameters.logGroupName : `/aws/lambda/${parameters.logGroupName}`; // First verify if the log group exists const logGroups = await cloudWatchLogsClient.send( new DescribeLogGroupsCommand({ logGroupNamePrefix: logGroupName, }) ); if (!logGroups.logGroups || logGroups.logGroups.length === 0) { // Get all available log groups for better error message const allLogGroups = await cloudWatchLogsClient.send( new DescribeLogGroupsCommand({}) ); return res.status(404).json({ error: `Log group '${logGroupName}' not found.`, availableLogGroups: allLogGroups.logGroups?.map((group) => group.logGroupName) || [], message: "Please use one of the available log groups listed above.", }); } const command = new FilterLogEventsCommand({ logGroupName: logGroupName, filterPattern: parameters.searchString || "", startTime: parameters.startTime, endTime: parameters.endTime, }); const response = await cloudWatchLogsClient.send(command); result = { events: response.events || [], nextToken: response.nextToken, logGroupName: logGroupName, }; } catch (error) { console.error("CloudWatch error:", error); if (error.name === "ResourceNotFoundException") { // Get all available log groups for better error message const allLogGroups = await cloudWatchLogsClient.send( new DescribeLogGroupsCommand({}) ); return res.status(404).json({ error: `Log group '${parameters.logGroupName}' not found.`, availableLogGroups: allLogGroups.logGroups?.map((group) => group.logGroupName) || [], message: "Please use one of the available log groups listed above.", }); } throw error; } } else { const executeResponse = await axios.post( `${CALCULATOR_API_URL}/${tool}`, parameters ); result = executeResponse.data; } return res.json({ explanation, result, toolUsed: tool, }); } catch (error) { console.error("Error processing message:", error); return res.status(500).json({ error: "Failed to process message", details: error.message, }); } }); // Health check endpoint app.get("/health", (req, res) => { res.json({ status: "ok" }); }); // Start the server const PORT = process.env.PORT || 3001; app.listen(PORT, () => { console.log(`MCP Server running on port ${PORT}`); }); module.exports = app;