ComfyUI MCP Server

Instructions

Implementation Reference

• src/tools/workflows.ts:93-129 (handler)

  Main handler function that executes the comfy_load_workflow tool by loading the workflow data and returning it as JSON, with error handling.

  export async function handleLoadWorkflow(input: LoadWorkflowInput) {
    try {
      const data = loadWorkflowFromLibrary(input.name);
  
      return {
        content: [{
          type: "text",
          text: JSON.stringify({
            name: data.name,
            workflow: data.workflow,
            description: data.description,
            tags: data.tags,
            created_at: data.created_at,
            updated_at: data.updated_at
          }, null, 2)
        }]
      };
    } catch (error: any) {
      if (error.message.includes('not found')) {
        return {
          content: [{
            type: "text",
            text: JSON.stringify(ComfyUIErrorBuilder.fileNotFound(input.name), null, 2)
          }],
          isError: true
        };
      }
  
      return {
        content: [{
          type: "text",
          text: JSON.stringify(ComfyUIErrorBuilder.executionError(error.message), null, 2)
        }],
        isError: true
      };
    }
  }

• src/utils/filesystem.ts:196-207 (helper)

  Helper function that performs the actual file reading and parsing of the workflow JSON from the library directory.

  export function loadWorkflowFromLibrary(name: string): any {
    const config = getConfig();
    const libraryPath = getFullPath(config.paths.workflow_library);
    const filePath = join(libraryPath, `${name}.json`);
  
    if (!existsSync(filePath)) {
      throw new Error(`Workflow not found: ${name}`);
    }
  
    const data = readFileSync(filePath, 'utf-8');
    return JSON.parse(data);
  }

• src/types/tools.ts:94-96 (schema)

  Zod schema defining the input for the tool: requires a 'name' string.

  export const LoadWorkflowSchema = z.object({
    name: z.string()
  });

• src/server.ts:97-101 (registration)

  Registration of the tool in the listTools response, specifying name, description, and input schema.

  {
    name: 'comfy_load_workflow',
    description: 'Load a saved workflow from the MCP library by name. Returns the workflow JSON and metadata.',
    inputSchema: zodToJsonSchema(LoadWorkflowSchema) as any,
  },

• src/server.ts:167-168 (registration)

  Dispatch case in the CallToolRequestHandler that routes to the handler function.

  case 'comfy_load_workflow':
    return await handleLoadWorkflow(args as any);