MCP Word Counter

Instructions

Implementation Reference

• src/wordCounter.ts:12-19 (handler)

  Core handler function that reads the file content and computes word count, total characters, and non-space characters.

  public async analyzeFile(filePath: string) {
    const text = await fs.readFile(filePath, 'utf-8');
    return {
      words: this.countWords(text),
      characters: this.countCharacters(text),
      charactersNoSpaces: this.countCharactersNoSpaces(text)
    };
  }

• src/index.ts:48-88 (handler)

  MCP server request handler for tool execution (CallToolRequestSchema) that specifically handles 'analyze_text' tool calls, including name check, parameter validation, delegation to WordCounter, response formatting, and error handling.

  server.setRequestHandler(CallToolRequestSchema, async (request) => {
    if (request.params.name !== "analyze_text") {
      throw new McpError(
        ErrorCode.MethodNotFound,
        `Unknown tool: ${request.params.name}`
      );
    }
  
    const filePath = request.params.arguments?.filePath;
    if (!filePath || typeof filePath !== "string") {
      throw new McpError(
        ErrorCode.InvalidParams,
        "File path parameter is required and must be a string"
      );
    }
  
    try {
      const stats = await wordCounter.analyzeFile(filePath);
      return {
        content: [
          {
            type: "text",
            text: `Analysis Results:
  • Word count: ${stats.words}
  • Character count (including spaces): ${stats.characters}
  • Character count (excluding spaces): ${stats.charactersNoSpaces}`
          }
        ]
      };
    } catch (error) {
      return {
        isError: true,
        content: [
          {
            type: "text",
            text: `Error analyzing file: ${error instanceof Error ? error.message : String(error)}`
          }
        ]
      };
    }
  });

• src/index.ts:30-45 (schema)

  Tool schema definition including name, description, and input schema requiring a 'filePath' string.

      {
        name: "analyze_text",
        description: "Count words and characters in a text document",
        inputSchema: {
          type: "object",
          properties: {
            filePath: {
              type: "string",
              description: "Path to the text file to analyze"
            }
          },
          required: ["filePath"]
        }
      }
    ]
  }));

• src/index.ts:28-45 (registration)

  Registers the ListToolsRequestHandler which exposes the 'analyze_text' tool with its schema.

  server.setRequestHandler(ListToolsRequestSchema, async () => ({
    tools: [
      {
        name: "analyze_text",
        description: "Count words and characters in a text document",
        inputSchema: {
          type: "object",
          properties: {
            filePath: {
              type: "string",
              description: "Path to the text file to analyze"
            }
          },
          required: ["filePath"]
        }
      }
    ]
  }));

• src/wordCounter.ts:25-34 (helper)

  Helper method for counting words by splitting text on whitespace sequences.

  private countWords(text: string): number {
    // Handle empty or whitespace-only strings
    if (!text.trim()) {
      return 0;
    }
  
    // Split by whitespace and filter out empty strings
    const words = text.trim().split(/\s+/).filter(word => word.length > 0);
    return words.length;
  }