update_block · Pl MCP: Risk & Policy

WHAT IT DOES

What update_block does on Pl

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

WHY IT NEEDS A POLICY

Why update_block needs a policy

This tool modifies existing blocks (likely UI/workflow components) reversibly. It is a Write operation since it changes data but does not delete or irreversibly destroy content. Severity is medium because misuse could corrupt project state or modify unintended workflow components, but changes are typically undoable in desktop applications.

From the tool's definition Tool name 'update_block' and description 'Update an existing block' indicate modification of existing data within Platforma Desktop projects.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_block Rate-limited

update_block 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": {
    "update_block": {
      "limits": [
        {
          "counter": "update_block_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 Pl, so you can run agents against it safely.

FAQ

Questions about update_block

What does the update_block tool do? +

Update an existing block. It is categorised as a Write tool in the Pl MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_block? +

Register the Pl MCP server in PolicyLayer and add a rule for update_block: 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 Pl. Nothing to install.

What risk level is update_block? +

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

Can I rate-limit update_block? +

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

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

update_block is provided by the Pl MCP server (@milaboratories/pl-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.