generate_variants · Stitch MCP Server MCP: Risk & Policy

WHAT IT DOES

What generate_variants does on Stitch MCP Server

AI agents use generate_variants to create or update resources in Stitch MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Stitch MCP Server environment.

WHY IT NEEDS A POLICY

Why generate_variants needs a policy

The tool creates or generates new design variants, which are new data artifacts. This is reversible (variants can be deleted) and has no irreversible consequences. It does not execute arbitrary code, delete data, or move financial resources. It fits the Write category—creating new design assets.

From the tool's definition Tool name 'generate_variants' and description 'Generates design variants of an existing screen' indicate creation of new design assets. This is a write operation that creates new data (design variants) based on existing designs.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

generate_variants Rate-limited

generate_variants stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "generate_variants": {
      "limits": [
        {
          "counter": "generate_variants_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Stitch MCP Server, so you can run agents against it safely.

FAQ

Questions about generate_variants

What does the generate_variants tool do? +

Generates design variants of an existing screen. It is categorised as a Write tool in the Stitch MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on generate_variants? +

Register the Stitch MCP Server MCP server in PolicyLayer and add a rule for generate_variants: 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 Stitch MCP Server. Nothing to install.

What risk level is generate_variants? +

generate_variants is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit generate_variants? +

Yes. Add a rate_limit block to the generate_variants 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 generate_variants completely? +

Set action: deny in the PolicyLayer policy for generate_variants. 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 generate_variants? +

generate_variants is provided by the Stitch MCP Server MCP server (oogleyskr/stitch-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.