set_fact · Claude Team MCP: Risk & Policy

WHAT IT DOES

What set_fact does on Claude Team MCP

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

WHY IT NEEDS A POLICY

Why set_fact needs a policy

This tool creates or modifies configuration/metadata stored as key-value pairs. The 'Overwrites same key' language confirms it performs Write operations (reversible updates). Severity is medium because overwriting facts could disrupt team coordination if critical values like 'base_url' or 'version' are corrupted by an agent, but the action is reversible by setting the correct value again.

From the tool's definition Tool description states 'Store a key-value fact' and 'Overwrites same key', indicating reversible creation and modification of data without permanent deletion.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_fact Rate-limited

set_fact 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_fact": {
      "limits": [
        {
          "counter": "set_fact_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 Claude Team MCP, so you can run agents against it safely.

FAQ

Questions about set_fact

What does the set_fact tool do? +

Store a key-value fact (deadline, version, base URL...). Overwrites same key. It is categorised as a Write tool in the Claude Team 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 set_fact? +

Register the Claude Team MCP server in PolicyLayer and add a rule for set_fact: 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 Claude Team MCP. Nothing to install.

What risk level is set_fact? +

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

Can I rate-limit set_fact? +

Yes. Add a rate_limit block to the set_fact 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_fact completely? +

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

set_fact is provided by the Claude Team MCP server (lakshan12367/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.