filesystem-mcp-server

Instructions

Implementation Reference

• src/mcp-server/tools/setFilesystemDefault/setFilesystemDefaultLogic.ts:29-40 (handler)

  Core handler function that executes the tool logic: sets the default filesystem path in serverState and returns confirmation.

  export const setFilesystemDefaultLogic = async (input: SetFilesystemDefaultInput, context: RequestContext): Promise<SetFilesystemDefaultOutput> => {
    const { path: newPath } = input;
  
    // The validation (absolute check, sanitization) happens within serverState.setDefaultFilesystemPath
    serverState.setDefaultFilesystemPath(newPath, context);
  
    const currentPath = serverState.getDefaultFilesystemPath();
    return {
      message: `Default filesystem path successfully set to: ${currentPath}`,
      currentDefaultPath: currentPath,
    };
  };

• src/mcp-server/tools/setFilesystemDefault/setFilesystemDefaultLogic.ts:7-10 (schema)

  Zod schema defining the input structure for the tool: requires an absolute path string.

  export const SetFilesystemDefaultInputSchema = z.object({
    path: z.string().min(1, 'Path cannot be empty')
      .describe('The absolute path to set as the default for resolving relative paths during this session.'),
  });

• src/mcp-server/tools/setFilesystemDefault/registration.ts:19-62 (registration)

  Registers the 'set_filesystem_default' tool on the MCP server instance, providing name, description, input schema, and an async handler that calls the core logic.

  export const registerSetFilesystemDefaultTool = async (server: McpServer): Promise<void> => {
    const registrationContext = requestContextService.createRequestContext({ operation: 'RegisterSetFilesystemDefaultTool' });
    logger.info("Attempting to register 'set_filesystem_default' tool", registrationContext);
  
    await ErrorHandler.tryCatch(
      async () => {
        server.tool(
          'set_filesystem_default', // Tool name
          'Sets a default absolute path for the current session. Relative paths used in other filesystem tools (like readFile) will be resolved against this default. The default is cleared on server restart.', // Description
          SetFilesystemDefaultInputSchema.shape, // Pass the schema shape
          async (params, extra) => {
            const typedParams = params as SetFilesystemDefaultInput;
            const callContext = requestContextService.createRequestContext({ operation: 'SetFilesystemDefaultToolExecution', parentId: registrationContext.requestId });
            logger.info(`Executing 'set_filesystem_default' tool with path: ${typedParams.path}`, callContext);
  
            // ErrorHandler will catch McpErrors thrown by the logic (e.g., non-absolute path)
            const result = await ErrorHandler.tryCatch(
              () => setFilesystemDefaultLogic(typedParams, callContext),
              {
                operation: 'setFilesystemDefaultLogic',
                context: callContext,
                input: typedParams, // Input is automatically sanitized by ErrorHandler
                errorCode: BaseErrorCode.INTERNAL_ERROR // Default error if unexpected failure
              }
            );
  
            logger.info(`Successfully executed 'set_filesystem_default'. Current default: ${result.currentDefaultPath}`, callContext);
  
            // Format the successful response
            return {
              content: [{ type: 'text', text: result.message }],
            };
          }
        );
        logger.info("'set_filesystem_default' tool registered successfully", registrationContext);
      },
      {
        operation: 'registerSetFilesystemDefaultTool',
        context: registrationContext,
        errorCode: BaseErrorCode.CONFIGURATION_ERROR,
        critical: true
      }
    );
  };

• src/mcp-server/server.ts:82-92 (registration)

  Top-level call to registerSetFilesystemDefaultTool as part of all filesystem tools during server initialization.

    registerReadFileTool(server),
    registerSetFilesystemDefaultTool(server),
    registerWriteFileTool(server),
    registerUpdateFileTool(server),
    registerListFilesTool(server),
    registerDeleteFileTool(server),
    registerDeleteDirectoryTool(server),
    registerCreateDirectoryTool(server),
    registerMovePathTool(server),
    registerCopyPathTool(server)
  ];

• src/mcp-server/tools/setFilesystemDefault/index.ts:1-2 (registration)

  Index file exporting the registration function for convenient import.

  export { registerSetFilesystemDefaultTool } from './registration.js';