sdk_fill_form · UI Bridge MCP: Risk & Policy

WHAT IT DOES

What sdk_fill_form does on UI Bridge MCP

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

WHY IT NEEDS A POLICY

Why sdk_fill_form needs a policy

Form-filling is a Write operation as it inputs/modifies data in UI forms. Given this is an SDK tool interacting with external applications (per server description), misuse could submit sensitive data or modify application state. Severity is high due to the potential blast radius of an AI agent autonomously filling forms in external applications, but confidence is reduced due to the empty description.

From the tool's definition Tool name 'sdk_fill_form' suggests filling out form fields, which creates or modifies data in UI elements. Description is empty, lowering confidence.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

sdk_fill_form Rate-limited

sdk_fill_form 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": {
    "sdk_fill_form": {
      "limits": [
        {
          "counter": "sdk_fill_form_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 UI Bridge MCP, so you can run agents against it safely.

FAQ

Questions about sdk_fill_form

What does the sdk_fill_form tool do? +

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

How do I enforce a policy on sdk_fill_form? +

Register the UI Bridge MCP server in PolicyLayer and add a rule for sdk_fill_form: 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 UI Bridge MCP. Nothing to install.

What risk level is sdk_fill_form? +

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

Can I rate-limit sdk_fill_form? +

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

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

sdk_fill_form is provided by the UI Bridge MCP server (qontinui/ui-bridge-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.