Fetch the first output image from a completed prompt and upload it to ComfyUI input folder. Returns the filename to use in LoadImage for a follow-up workflow (e.g. image caption / verification). Use after get_execution_status confirms the prompt finished with image output. Requires COMFYUI_HOST.
Part of the ComfyUI Builder server.
Free to start. No card required.
AI agents use prepare_image_for_workflow to create or modify resources in ComfyUI Builder. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call prepare_image_for_workflow repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach ComfyUI Builder.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"prepare_image_for_workflow": {
"limits": [
{
"counter": "prepare_image_for_workflow_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full ComfyUI Builder policy for all 60 tools.
These attack patterns abuse exactly the kind of access prepare_image_for_workflow gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Fetch the first output image from a completed prompt and upload it to ComfyUI input folder. Returns the filename to use in LoadImage for a follow-up workflow (e.g. image caption / verification). Use after get_execution_status confirms the prompt finished with image output. Requires COMFYUI_HOST.. It is categorised as a Write tool in the ComfyUI Builder MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the ComfyUI Builder MCP server in PolicyLayer and add a rule for prepare_image_for_workflow: 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 Builder. Nothing to install.
prepare_image_for_workflow is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the prepare_image_for_workflow 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.
Set action: deny in the PolicyLayer policy for prepare_image_for_workflow. 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.
prepare_image_for_workflow is provided by the ComfyUI Builder MCP server (mcp-comfy-ui-builder). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 60 ComfyUI Builder tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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