Copy-Paste MCP

Instructions

Implementation Reference

• src/index.ts:20-78 (handler)

  The handler function that implements the extract-lines tool logic: validates input line numbers, splits text into lines, extracts the specified range, and returns the result or an error.

  async ({ text, start_line, end_line }) => {
      try {
          // Validate line numbers
          if (start_line > end_line) {
              return {
                  isError: true,
                  content: [
                      {
                          type: "text",
                          text: `Error: Start line (${start_line}) cannot be greater than end line (${end_line}).`,
                      },
                  ],
              };
          }
  
          // Split the text into lines
          const allLines = text.split('\n');
          
          // Validate that requested lines are within range
          if (start_line > allLines.length) {
              return {
                  isError: true,
                  content: [
                      {
                          type: "text",
                          text: `Error: Start line (${start_line}) exceeds the total number of lines (${allLines.length}).`,
                      },
                  ],
              };
          }
  
          // Extract the requested lines (adjusting for 0-based array indexing)
          const extractedLines = allLines.slice(
              start_line - 1, 
              Math.min(end_line, allLines.length)
          );
  
          // Return the extracted lines
          return {
              content: [
                  {
                      type: "text",
                      text: extractedLines.join('\n'),
                  },
              ],
          };
      } catch (error: unknown) {
          const errorMessage = error instanceof Error ? error.message : String(error);
          return {
              isError: true,
              content: [
                  {
                      type: "text",
                      text: `Error extracting lines: ${errorMessage}`,
                  },
              ],
          };
      }
  }

• src/index.ts:16-19 (schema)

  Zod schema for the tool's input parameters: text (string), start_line (integer >=1), end_line (integer).

      text: z.string().describe("The full text content to extract lines from"),
      start_line: z.number().int().min(1).describe("Starting line number (inclusive)"),
      end_line: z.number().int().describe("Ending line number (inclusive)"),
  },

• src/index.ts:13-79 (registration)

  Registration of the 'extract-lines' tool on the MCP server, specifying name, description, input schema, and handler function.

      "extract-lines",
      "Extract a specific range of lines from text content",
      {
          text: z.string().describe("The full text content to extract lines from"),
          start_line: z.number().int().min(1).describe("Starting line number (inclusive)"),
          end_line: z.number().int().describe("Ending line number (inclusive)"),
      },
      async ({ text, start_line, end_line }) => {
          try {
              // Validate line numbers
              if (start_line > end_line) {
                  return {
                      isError: true,
                      content: [
                          {
                              type: "text",
                              text: `Error: Start line (${start_line}) cannot be greater than end line (${end_line}).`,
                          },
                      ],
                  };
              }
  
              // Split the text into lines
              const allLines = text.split('\n');
              
              // Validate that requested lines are within range
              if (start_line > allLines.length) {
                  return {
                      isError: true,
                      content: [
                          {
                              type: "text",
                              text: `Error: Start line (${start_line}) exceeds the total number of lines (${allLines.length}).`,
                          },
                      ],
                  };
              }
  
              // Extract the requested lines (adjusting for 0-based array indexing)
              const extractedLines = allLines.slice(
                  start_line - 1, 
                  Math.min(end_line, allLines.length)
              );
  
              // Return the extracted lines
              return {
                  content: [
                      {
                          type: "text",
                          text: extractedLines.join('\n'),
                      },
                  ],
              };
          } catch (error: unknown) {
              const errorMessage = error instanceof Error ? error.message : String(error);
              return {
                  isError: true,
                  content: [
                      {
                          type: "text",
                          text: `Error extracting lines: ${errorMessage}`,
                      },
                  ],
              };
          }
      }
  );