set_instance_overrides

THE RISK

Medium Risk

Why set_instance_overrides needs a policy

This tool modifies existing design data (component instances and their override properties) but does not delete or irreversibly destroy content. The changes are reversible through Figma's undo functionality or by applying different overrides. It is Write rather than Execute because the operation is a direct data modification action, not arbitrary code execution.

From the tool's definition Tool description states it will 'Apply previously copied overrides to selected component instances' and 'all copied override properties will be applied.' The verb 'Apply' combined with modifying component instance properties indicates data modification.

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

POLICY

How to control set_instance_overrides

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

policy.json

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

set_instance_overrides 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.

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

LIMIT THIS TOOL →

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EXPLORE

Related tools and policies

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All 64 Figma AI Bridge tools →

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about set_instance_overrides

What does the set_instance_overrides tool do? +

Apply previously copied overrides to selected component instances. Target instances will be swapped to the source component and all copied override properties will be applied. It is categorised as a Write tool in the Figma AI Bridge MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_instance_overrides? +

Register the Figma AI Bridge MCP server in PolicyLayer and add a rule for set_instance_overrides: 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 Figma AI Bridge. Nothing to install.

What risk level is set_instance_overrides? +

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

Can I rate-limit set_instance_overrides? +

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

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

set_instance_overrides is provided by the Figma AI Bridge MCP server (renfei-design/figma_ai_bridge). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Figma AI Bridge tool call.

Start from Figma AI Bridge, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →