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Common questions about the RunComfy MCP server.

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What deployments can I access?

The MCP server uses your API token to call the RunComfy Serverless API. You see exactly the same deployments as on your Deployments dashboard — both ComfyUI workflow deployments and LoRA deployments.

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Which sign-in method should I use?

Two ways to authenticate, both tied to an API token from your Profile: If you’re unsure, use the API token header — it’s one command and works with every client that allows custom headers. ChatGPT is the exception: it allows no custom headers, so it must use browser sign-in.

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How is my API token handled?

It depends on which sign-in method you use. API token header — your token is sent on each request, verified against api.runcomfy.net, and forwarded upstream for that request only. It is never written to disk by the MCP server and never logged. Browser sign-in — your token is verified, then stored encrypted in the OAuth grant so the server can act on your behalf later. Your MCP client never receives it; it gets a separate, short-lived access token instead. Either way, every tool call is re-checked against RunComfy before it runs, so regenerating the token in your Profile revokes access immediately — for the header and for any browser sign-in built on it.

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What does it cost?

The MCP server itself is free. You pay only for the RunComfy resources you use:
  • Inference requests are billed the same as calling the Serverless API directly
  • Deployments with min_instances > 0 incur GPU uptime charges even when idle
  • Deployments with min_instances = 0 cost nothing when idle (scale-to-zero)
See Serverless API Billing for pricing details.

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How do I pass images or videos as inputs?

When a workflow node requires an image, video, or audio file, pass the input directly in the overrides object of submit_request:
  • Public HTTPS URL (recommended): "image": "https://example.com/photo.jpg" — use a URL that returns the raw file without authentication
  • Base64 data URI: "image": "data:image/jpeg;base64,/9j/4AAQ..." — for inline content
No separate upload step is needed. See Async Queue Endpoints for more details and examples.

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Are there rate limits?

Your requests are subject to the same rate limits as the RunComfy Serverless API. The MCP server adds one limit of its own: 600 token-authenticated requests per minute per IP address. This exists to stop token guessing and is far above normal assistant use — if you hit it you’ll get a 429, and waiting a minute clears it.

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How do I find node IDs for my workflow?

Call get_deployment with include_payload=true. The response includes a payload_summary with every node’s ID, class type, and input names. Use these to build the overrides object for submit_request. For example, if the summary shows node_id: "6" with class_type: "CLIPTextEncode" and input_names: ["text", "clip"], your override would be:
For more context on workflow files and node schemas, see Workflow Files.

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Can I use a different workflow without redeploying?

Yes. The submit_request tool accepts an optional workflow_api_json parameter that lets you send a full ComfyUI workflow inline. The deployment’s stored workflow is bypassed for that request. This is useful for testing workflow changes before updating the deployment. See Async Queue Endpoints — Send dynamic workflow for details.

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Does it work with ChatGPT?

Yes, using browser sign-in. ChatGPT does not support custom headers on MCP connectors, so the API token header is not an option there — OAuth is the only way in. At chatgpt.com (not the desktop app), turn on Developer mode under Settings → Security and login, then open Plugins, select +, and create a developer-mode app pointing at https://mcp.runcomfy.com/mcp with OAuth authentication. A RunComfy page opens where you paste an API token from your Profile once.
Not available in the Mac app or on iPhone. Adding a custom MCP server needs Developer mode, which only exists at chatgpt.com and in the Windows app. A connector added on the web syncs to the Mac app and shows up in settings, but cannot be switched on there. This is an OpenAI platform limit, not a RunComfy one.
No “Connectors” in your settings? OpenAI renamed it in July 2026 — Connectors is now Plugins, and Developer mode moved out of Connectors → Advanced into Settings → Security and login.
RunComfy’s tools are for managing deployments and running inference. They are not the search and fetch pair that ChatGPT’s deep research feature specifically requires, so use the connector from normal chat or developer mode rather than deep research.

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Why does my client need a “loopback” redirect URI?

Browser sign-in is open to any local client that receives its callback on http://localhost, http://127.0.0.1, or http://[::1] — that covers Claude Code, Hermes Agent, OpenClaw, and most desktop MCP clients. Hosted clients that receive the callback on their own servers must be allowlisted individually — currently Claude.ai and ChatGPT. This keeps someone from registering a lookalike client, sending you a link to a genuine-looking RunComfy consent page, and collecting your token. A loopback callback can only ever deliver to your own machine. If a client can’t do either, use the API token header instead — it works with every Streamable HTTP client.

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Where can I learn more about the Serverless API?

The MCP tools map directly to the Serverless API endpoints: