ComfyUI MCP Server

Instructions

Implementation Reference

• src/tools/workflows.ts:20-91 (handler)

  The main handler function for the 'comfy_save_workflow' tool. Validates input, processes the workflow JSON, checks for overwrites, creates metadata, and saves it to the workflow library using saveWorkflowToLibrary.

  export async function handleSaveWorkflow(input: SaveWorkflowInput) {
    try {
      // Validate workflow name
      if (!validateWorkflowName(input.name)) {
        throw ComfyUIErrorBuilder.validationError(
          'Invalid workflow name. Use only alphanumeric characters, hyphens, and underscores.'
        );
      }
  
      // Parse and validate workflow
      const processor = new WorkflowProcessor();
      const workflow = processor.parseWorkflow(input.workflow);
  
      if (!validateWorkflowJSON(workflow)) {
        throw ComfyUIErrorBuilder.invalidWorkflow('Invalid workflow structure');
      }
  
      // Check if exists and overwrite is false
      const config = getConfig();
      const libraryPath = getFullPath(config.paths.workflow_library);
      const filePath = join(libraryPath, `${input.name}.json`);
  
      if (existsSync(filePath) && !input.overwrite) {
        throw ComfyUIErrorBuilder.validationError(
          `Workflow "${input.name}" already exists. Set overwrite=true to replace it.`
        );
      }
  
      // Create metadata
      const now = new Date().toISOString();
      const metadata = {
        name: input.name,
        description: input.description,
        tags: input.tags || [],
        created_at: existsSync(filePath) ? JSON.parse(require('fs').readFileSync(filePath, 'utf-8')).created_at : now,
        updated_at: now,
        workflow
      };
  
      // Save to library
      const savedPath = saveWorkflowToLibrary(input.name, metadata);
  
      return {
        content: [{
          type: "text",
          text: JSON.stringify({
            name: input.name,
            path: savedPath,
            message: `Workflow "${input.name}" saved successfully`
          }, null, 2)
        }]
      };
    } catch (error: any) {
      if (error.error) {
        return {
          content: [{
            type: "text",
            text: JSON.stringify(error, null, 2)
          }],
          isError: true
        };
      }
  
      return {
        content: [{
          type: "text",
          text: JSON.stringify(ComfyUIErrorBuilder.executionError(error.message), null, 2)
        }],
        isError: true
      };
    }
  }

• src/server.ts:93-96 (registration)

  Registration of the 'comfy_save_workflow' tool in the MCP server, including name, description, and input schema reference.

    name: 'comfy_save_workflow',
    description: 'Save a workflow JSON to the MCP library for later reuse. Includes metadata like description and tags for organization.',
    inputSchema: zodToJsonSchema(SaveWorkflowSchema) as any,
  },

• src/types/tools.ts:85-91 (schema)

  Zod schema defining the input structure for the 'comfy_save_workflow' tool, including validation for name, workflow, description, tags, and overwrite flag.

  export const SaveWorkflowSchema = z.object({
    name: z.string().regex(/^[a-zA-Z0-9_-]+$/),
    workflow: z.union([z.string(), z.record(z.any())]),
    description: z.string().optional(),
    tags: z.array(z.string()).optional(),
    overwrite: z.boolean().optional().default(false)
  });

• src/server.ts:164-165 (registration)

  Switch case in the tool call handler that routes 'comfy_save_workflow' calls to the handleSaveWorkflow function.

  case 'comfy_save_workflow':
    return await handleSaveWorkflow(args as any);