filesystem-mcp-server

Instructions

Implementation Reference

• src/mcp-server/tools/createDirectory/createDirectoryLogic.ts:34-89 (handler)

  Core handler function that implements the 'create_directory' tool logic, resolving paths, checking existence, and creating directories with fs.mkdir.

  export const createDirectoryLogic = async (input: CreateDirectoryInput, context: RequestContext): Promise<CreateDirectoryOutput> => {
    const { path: requestedPath, create_parents } = input;
    const logicContext = { ...context, tool: 'createDirectoryLogic', create_parents };
    logger.debug(`createDirectoryLogic: Received request to create directory "${requestedPath}"`, logicContext);
  
    // Resolve the path
    const absolutePath = serverState.resolvePath(requestedPath, context);
    logger.debug(`createDirectoryLogic: Resolved path to "${absolutePath}"`, { ...logicContext, requestedPath });
  
    try {
      // Check if path already exists
      try {
        const stats = await fs.stat(absolutePath);
        if (stats.isDirectory()) {
          logger.info(`createDirectoryLogic: Directory already exists at "${absolutePath}"`, { ...logicContext, requestedPath });
          // Directory already exists, consider this a success (idempotent)
          return {
            message: `Directory already exists: ${absolutePath}`,
            createdPath: absolutePath,
            parentsCreated: false, // No parents needed to be created now
          };
        } else {
          // Path exists but is not a directory (e.g., a file)
          logger.error(`createDirectoryLogic: Path exists but is not a directory "${absolutePath}"`, { ...logicContext, requestedPath });
          throw new McpError(BaseErrorCode.VALIDATION_ERROR, `Path already exists but is not a directory: ${absolutePath}`, { ...logicContext, requestedPath, resolvedPath: absolutePath });
        }
      } catch (statError: any) {
        if (statError.code !== 'ENOENT') {
          // If error is something other than "Not Found", re-throw it
          throw statError;
        }
        // Path does not exist, proceed with creation
        logger.debug(`createDirectoryLogic: Path does not exist, proceeding with creation "${absolutePath}"`, { ...logicContext, requestedPath });
      }
  
      // Attempt to create the directory
      await fs.mkdir(absolutePath, { recursive: create_parents });
      logger.info(`createDirectoryLogic: Successfully created directory "${absolutePath}" (parents: ${create_parents})`, { ...logicContext, requestedPath });
  
      return {
        message: `Successfully created directory: ${absolutePath}${create_parents ? ' (including parents if needed)' : ''}`,
        createdPath: absolutePath,
        parentsCreated: create_parents, // Reflects the *option* enabled, not necessarily if they *were* created
      };
  
    } catch (error: any) {
      logger.error(`createDirectoryLogic: Error creating directory "${absolutePath}"`, { ...logicContext, requestedPath, error: error.message, code: error.code });
  
      if (error instanceof McpError) {
        throw error; // Re-throw known McpErrors
      }
  
      // Handle potential I/O errors (e.g., permissions, invalid path components)
      throw new McpError(BaseErrorCode.INTERNAL_ERROR, `Failed to create directory: ${error.message || 'Unknown I/O error'}`, { ...logicContext, requestedPath, resolvedPath: absolutePath, originalError: error });
    }
  };

• src/mcp-server/tools/createDirectory/createDirectoryLogic.ts:9-14 (schema)

  Zod schema defining the input parameters for the 'create_directory' tool: path (string) and create_parents (boolean).

  export const CreateDirectoryInputSchema = z.object({
    path: z.string().min(1, 'Path cannot be empty')
      .describe('The path to the directory to create. Can be relative or absolute.'),
    create_parents: z.boolean().default(true)
      .describe('If true, create any necessary parent directories that don\'t exist. If false, fail if a parent directory is missing.'),
  });

• src/mcp-server/tools/createDirectory/registration.ts:19-71 (registration)

  Registration function that calls server.tool('create_directory', ...) with input schema, description, and a wrapper handler that validates input and delegates to createDirectoryLogic.

  export const registerCreateDirectoryTool = async (server: McpServer): Promise<void> => {
    const registrationContext = requestContextService.createRequestContext({ operation: 'RegisterCreateDirectoryTool' });
    logger.info("Attempting to register 'create_directory' tool", registrationContext);
  
    await ErrorHandler.tryCatch(
      async () => {
        server.tool(
          'create_directory', // Tool name
          'Creates a directory. Optionally creates parent directories. Accepts relative or absolute paths.', // Description
          CreateDirectoryInputSchema.shape, // Pass the schema shape
          async (params, extra) => {
            // Validate input using the Zod schema
            const validationResult = CreateDirectoryInputSchema.safeParse(params);
            if (!validationResult.success) {
              const errorContext = requestContextService.createRequestContext({ operation: 'CreateDirectoryToolValidation' });
              logger.error('Invalid input parameters for create_directory tool', { ...errorContext, errors: validationResult.error.errors });
              throw new McpError(BaseErrorCode.VALIDATION_ERROR, `Invalid parameters: ${validationResult.error.errors.map(e => `${e.path.join('.')} - ${e.message}`).join(', ')}`, errorContext);
            }
            const typedParams = validationResult.data; // Use validated data
  
            // Create context for this execution
            const callContext = requestContextService.createRequestContext({ operation: 'CreateDirectoryToolExecution' });
            logger.info(`Executing 'create_directory' tool for path: ${typedParams.path}, create_parents: ${typedParams.create_parents}`, callContext);
  
            // ErrorHandler will catch McpErrors thrown by the logic
            const result = await ErrorHandler.tryCatch(
              () => createDirectoryLogic(typedParams, callContext),
              {
                operation: 'createDirectoryLogic',
                context: callContext,
                input: sanitization.sanitizeForLogging(typedParams), // Sanitize path
                errorCode: BaseErrorCode.INTERNAL_ERROR
              }
            );
  
            logger.info(`Successfully executed 'create_directory' for path: ${result.createdPath}, parentsCreated: ${result.parentsCreated}`, callContext);
  
            // Format the successful response
            return {
              content: [{ type: 'text', text: result.message }],
            };
          }
        );
        logger.info("'create_directory' tool registered successfully", registrationContext);
      },
      {
        operation: 'registerCreateDirectoryTool',
        context: registrationContext,
        errorCode: BaseErrorCode.CONFIGURATION_ERROR,
        critical: true
      }
    );
  };

• src/mcp-server/server.ts:89-89 (registration)

  Top-level call to register the 'create_directory' tool during server initialization.

  registerCreateDirectoryTool(server),