generate_with_workflow

Instructions

Implementation Reference

• src/tools/generate.ts:132-144 (handler)

  Handler function for the 'generate_with_workflow' tool. Takes a 'workflow' parameter (full ComfyUI node graph JSON), casts it to Workflow type, calls client.runWorkflow(), and returns image URLs in a text result.

  server.tool(
    "generate_with_workflow",
    "Submit an arbitrary ComfyUI workflow (full node graph) and return the resulting image URLs. Use this when you need a custom workflow like ControlNet, upscaling, or a node graph exported from ComfyUI's 'Save (API Format)'.",
    generateWithWorkflowSchema,
    async (args) => {
      const workflow = args.workflow as Workflow;
      const result = await client.runWorkflow(workflow);
      return textResult(
        `Workflow submitted (prompt_id: ${result.promptId}), ${result.images.length} image(s):`,
        result.images,
      );
    },
  );

• src/tools/generate.ts:68-74 (schema)

  Input schema for 'generate_with_workflow'. Defines a single required parameter 'workflow' as a record of string to any (the ComfyUI workflow JSON node graph).

  const generateWithWorkflowSchema = {
    workflow: z
      .record(z.string(), z.any())
      .describe(
        "Complete ComfyUI workflow JSON (node graph as returned by ComfyUI's 'Save (API Format)' export)",
      ),
  };

• src/tools/generate.ts:76-145 (registration)

  Registration of the 'generate_with_workflow' tool via server.tool() inside registerGenerateTools(), which is called from src/server.ts line 42.

  export function registerGenerateTools(
    server: McpServer,
    client: ComfyUIClient,
  ): void {
    server.tool(
      "generate_image",
      "Generate an image from a text prompt using ComfyUI's default txt2img workflow. Returns one or more image URLs served directly by the ComfyUI instance.",
      generateImageSchema,
      async (args) => {
        const result = await client.generate({
          prompt: args.prompt,
          negativePrompt: args.negative_prompt,
          width: args.width,
          height: args.height,
          steps: args.steps,
          cfg: args.cfg,
          seed: args.seed,
          checkpoint: args.checkpoint,
        });
  
        return textResult(
          `Generated ${result.images.length} image(s) (prompt_id: ${result.promptId}):`,
          result.images,
        );
      },
    );
  
    server.tool(
      "generate_variations",
      "Generate multiple variations of the same prompt by varying the seed. Useful for picking the best result or exploring a concept.",
      generateVariationsSchema,
      async (args) => {
        const startSeed = args.base_seed ?? Math.floor(Math.random() * 2 ** 32);
        const results = await Promise.all(
          Array.from({ length: args.count }, (_, i) =>
            client.generate({
              prompt: args.prompt,
              negativePrompt: args.negative_prompt,
              width: args.width,
              height: args.height,
              steps: args.steps,
              cfg: args.cfg,
              seed: startSeed + i,
              checkpoint: args.checkpoint,
            }),
          ),
        );
  
        const urls = results.flatMap((r) => r.images);
        return textResult(
          `Generated ${args.count} variation(s) starting from seed ${startSeed}:`,
          urls,
        );
      },
    );
  
    server.tool(
      "generate_with_workflow",
      "Submit an arbitrary ComfyUI workflow (full node graph) and return the resulting image URLs. Use this when you need a custom workflow like ControlNet, upscaling, or a node graph exported from ComfyUI's 'Save (API Format)'.",
      generateWithWorkflowSchema,
      async (args) => {
        const workflow = args.workflow as Workflow;
        const result = await client.runWorkflow(workflow);
        return textResult(
          `Workflow submitted (prompt_id: ${result.promptId}), ${result.images.length} image(s):`,
          result.images,
        );
      },
    );
  }

• src/comfyui/client.ts:61-68 (helper)

  The actual workflow execution engine. runWorkflow() submits the workflow JSON to ComfyUI's /prompt endpoint and waits for completion, returning extracted image URLs.

  async runWorkflow(workflow: Workflow): Promise<GenerateResult> {
    const { prompt_id } = await this.submit(workflow);
    const entry = await this.waitForCompletion(prompt_id);
    return {
      promptId: prompt_id,
      images: extractImageUrls(entry, this.publicUrl),
    };
  }

• src/comfyui/types.ts:18-24 (helper)

  Type definitions: Workflow (Record<string, WorkflowNode>) and WorkflowNode interface used by the handler to type-check the incoming workflow argument.

  export interface WorkflowNode {
    inputs: Record<string, unknown>;
    class_type: string;
    _meta?: Record<string, unknown>;
  }
  
  export type Workflow = Record<string, WorkflowNode>;