create_rectangular_mask · Bedrock Image MCP: Risk & Policy

WHAT IT DOES

What create_rectangular_mask does on Bedrock Image

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

WHY IT NEEDS A POLICY

Why create_rectangular_mask needs a policy

This tool creates (Write) a rectangular mask, likely a data structure or image layer used for image processing operations. Masks are reversible image artifacts that can be modified or deleted. The operation is non-destructive and does not directly alter underlying image data. Confidence is moderate (0.75) because the tool description is empty, requiring inference from the tool name and context of sibling tools.

From the tool's definition Tool name 'create_rectangular_mask' indicates creation of a mask object/resource. Sibling tools include 'create_ellipse_mask' and 'create_full_mask', establishing a pattern of mask creation operations within an image editing context.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_rectangular_mask Rate-limited

create_rectangular_mask 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": {
    "create_rectangular_mask": {
      "limits": [
        {
          "counter": "create_rectangular_mask_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 Bedrock Image, so you can run agents against it safely.

FAQ

Questions about create_rectangular_mask

What does the create_rectangular_mask tool do? +

create_rectangular_mask. It is categorised as a Write tool in the Bedrock Image MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_rectangular_mask? +

Register the Bedrock Image MCP server in PolicyLayer and add a rule for create_rectangular_mask: 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 Bedrock Image. Nothing to install.

What risk level is create_rectangular_mask? +

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

Can I rate-limit create_rectangular_mask? +

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

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

create_rectangular_mask is provided by the Bedrock Image MCP server (kalleeh/bedrock-image-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.