set_block_data · Pl MCP: Risk & Policy

WHAT IT DOES

What set_block_data does on Pl

AI agents use set_block_data 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 set_block_data needs a policy

This tool creates or modifies data within a block in Platforma Desktop. The action is reversible (data can be changed again) and does not delete, overwrite irreversibly, move money, or execute arbitrary external code. It fits the Write category. Severity is medium because incorrect data changes could affect project state and dependent blocks, but the effect is localized to a single block and reversible.

From the tool's definition "Set the user-facing data of a block (triggers args derivation and staging)" — the tool explicitly modifies data ('Set') and triggers downstream operations ('args derivation and staging'). The description confirms reversible data modification without deletion.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_block_data Rate-limited

set_block_data 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": {
    "set_block_data": {
      "limits": [
        {
          "counter": "set_block_data_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 set_block_data

What does the set_block_data tool do? +

Set the user-facing data of a block (triggers args derivation and staging). 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 set_block_data? +

Register the Pl MCP server in PolicyLayer and add a rule for set_block_data: 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 set_block_data? +

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

Can I rate-limit set_block_data? +

Yes. Add a rate_limit block to the set_block_data 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_block_data completely? +

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

set_block_data 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.