set_visibility · Small MCP: Risk & Policy

WHAT IT DOES

What set_visibility does on Small

AI agents invoke set_visibility to trigger actions in Small. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why set_visibility needs a policy

'Toggle visibility of a tool group' implies changing the operational state of tool availability within the session — this is an action with session-scoped side effects, not a simple read. It dynamically alters which tools are accessible, which could be misused to hide or expose functionality.

From the tool's definition Toggle visibility of a tool group for this session

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_visibility Rate-limited

set_visibility stays usable, but rate-capped — a runaway agent can't fire it dozens of times 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_visibility": {
      "limits": [
        {
          "counter": "set_visibility_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Small, so you can run agents against it safely.

FAQ

Questions about set_visibility

What does the set_visibility tool do? +

Toggle visibility of a tool group for this session. It is categorised as a Execute tool in the Small MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on set_visibility? +

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

What risk level is set_visibility? +

set_visibility is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit set_visibility? +

Yes. Add a rate_limit block to the set_visibility 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_visibility completely? +

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

set_visibility is provided by the Small MCP server (nishant-iit/smallmp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.