comfy_cancel_generation

Cancel an active AI image generation or remove pending tasks from the ComfyUI queue to manage workflow execution.

Instructions

Cancel a specific generation or interrupt the currently executing generation. Can optionally remove from queue.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`prompt_id`	No
`delete_from_queue`	No

Implementation Reference

src/tools/queue.ts:49-103 (handler)

The main handler function that implements the tool logic: interrupts the ComfyUI generation using the client, optionally deletes a specific queue item by prompt_id, and returns success/error responses.

export async function handleCancelGeneration(input: CancelGenerationInput) {
  try {
    const client = getComfyUIClient();

    if (input.prompt_id) {
      // Cancel specific prompt
      if (input.delete_from_queue) {
        await client.deleteQueueItem(input.prompt_id);
      }
      await client.interrupt();

      return {
        content: [{
          type: "text",
          text: JSON.stringify({
            cancelled: true,
            prompt_id: input.prompt_id,
            message: `Generation ${input.prompt_id} cancelled`
          }, null, 2)
        }]
      };
    } else {
      // Interrupt current
      await client.interrupt();

      return {
        content: [{
          type: "text",
          text: JSON.stringify({
            cancelled: true,
            message: "Current generation interrupted"
          }, 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/types/tools.ts:111-114 (schema)
Zod schema for input validation: optional prompt_id (to target specific generation) and delete_from_queue (default true).
```
export const CancelGenerationSchema = z.object({
  prompt_id: z.string().optional(),
  delete_from_queue: z.boolean().optional().default(true)
});
```

src/server.ts:120-124 (registration)

Tool registration in the ListTools response: defines name, description, and references the input schema.

{
  name: 'comfy_cancel_generation',
  description: 'Cancel a specific generation or interrupt the currently executing generation. Can optionally remove from queue.',
  inputSchema: zodToJsonSchema(CancelGenerationSchema) as any,
},

src/server.ts:179-180 (registration)
Switch case in CallToolRequestHandler that dispatches the tool call to the handler function.
```
case 'comfy_cancel_generation':
  return await handleCancelGeneration(args as any);
```

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