comfy_cancel_generation

THE RISK

High Risk

Why comfy_cancel_generation needs a policy

This tool interrupts an actively running process (image generation) and optionally removes items from the queue. It is an external operation that affects the execution state of the ComfyUI system. While it stops rather than starts a process, interrupting execution and modifying queue state is an Execute-category action.

From the tool's definition Cancel a specific generation or interrupt the currently executing generation. Can optionally remove from queue.

Documented attack patterns abuse exactly the kind of access comfy_cancel_generation gives an agent:

POLICY

How to control comfy_cancel_generation

PolicyLayer is an MCP gateway — it sits between your AI agents and ComfyUI MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for comfy_cancel_generation:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "comfy_cancel_generation": {
      "limits": [
        {
          "counter": "comfy_cancel_generation_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

comfy_cancel_generation stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register ComfyUI MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More ComfyUI MCP Server tools

Destructive comfy_clear_queue Clear all pending items from the queue (does not affect currently running generation). Req Destructive comfy_delete_workflow Delete a saved workflow from the MCP library. Requires confirmation for safety. Execute comfy_wait_for_completion Block until a generation completes or fails. Returns final outputs with image paths. Usefu Execute comfy_generate_simple Quick image generation using pre-configured workflow templates (flux_txt2img, sd15_txt2img Execute comfy_submit_workflow Submit a complete workflow JSON to ComfyUI for execution. Supports parameter overrides for Write comfy_save_workflow Save a workflow JSON to the MCP library for later reuse. Includes metadata like descriptio Write comfy_upload_image Upload an image to ComfyUI\ Read comfy_get_output_images List recent output images from ComfyUI\

All 14 ComfyUI MCP Server tools →

Execute tools on other servers

Android Forensics ADB MCP Server adb_shell_command EMBA-MCP run_emba_scan Frida Game Hacking MCP remove_breakpoint Procmon request_elevation

Go deeper

High-risk tools in ComfyUI MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about comfy_cancel_generation

What does the comfy_cancel_generation tool do? +

Cancel a specific generation or interrupt the currently executing generation. Can optionally remove from queue. It is categorised as a Execute tool in the ComfyUI MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on comfy_cancel_generation? +

Register the ComfyUI MCP Server MCP server in PolicyLayer and add a rule for comfy_cancel_generation: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches ComfyUI MCP Server. Nothing to install.

What risk level is comfy_cancel_generation? +

comfy_cancel_generation is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit comfy_cancel_generation? +

Yes. Add a rate_limit block to the comfy_cancel_generation rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block comfy_cancel_generation completely? +

Set action: deny in the PolicyLayer policy for comfy_cancel_generation. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides comfy_cancel_generation? +

comfy_cancel_generation is provided by the ComfyUI MCP Server MCP server (nikolaibibo/claude-comfyui-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every ComfyUI MCP Server tool call.

Start from ComfyUI MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →