km_add_set_variable

THE RISK

Medium Risk

Why km_add_set_variable needs a policy

This tool creates or modifies variable data within the Keyboard Maestro automation system. It is reversible (variables can be changed again) and has no permanent destructive effect. However, it carries medium severity because setting variables in an automation context could lead to unintended macro behavior if an agent sets critical variables without proper understanding of their downstream effects.

From the tool's definition Tool name 'km_add_set_variable' and description 'Add an action to set a variable to a text value' indicate creation/modification of variable state within Keyboard Maestro macros.

Documented attack patterns abuse exactly the kind of access km_add_set_variable gives an agent:

POLICY

How to control km_add_set_variable

PolicyLayer is an MCP gateway — it sits between your AI agents and Keyboard Maestro, and nothing reaches the server without passing your rules. This is the rule we recommend for km_add_set_variable:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "km_add_set_variable": {
      "limits": [
        {
          "counter": "km_add_set_variable_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

km_add_set_variable 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.

Create a free account and register Keyboard Maestro — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

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EXPLORE

Related tools and policies

More Keyboard Maestro tools

Destructive km_delete_action Delete a specific action from a macro. Actions are 1-indexed. WARNING: This cannot be undo Destructive km_delete_macro Delete a macro by name or UID. WARNING: This cannot be undone! Destructive km_delete_trigger Delete a trigger from a macro. Triggers are 1-indexed. Destructive km_manage_group Manage macro groups (create, delete, toggle, list). Execute km_run_macro Execute a macro by name or UID. Execute km_add_execute_macro Add an action to execute another macro. Execute km_add_shell_script Add an action to execute a shell script. Write km_search_replace_action Search and replace text within a specific action in a macro. Useful for fixing typos or up

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Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about km_add_set_variable

What does the km_add_set_variable tool do? +

Add an action to set a variable to a text value. It is categorised as a Write tool in the Keyboard Maestro MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on km_add_set_variable? +

Register the Keyboard Maestro MCP server in PolicyLayer and add a rule for km_add_set_variable: 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 Keyboard Maestro. Nothing to install.

What risk level is km_add_set_variable? +

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

Can I rate-limit km_add_set_variable? +

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

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

km_add_set_variable is provided by the Keyboard Maestro MCP server (saihgupr/keyboard-maestro-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Keyboard Maestro tool call.

Start from Keyboard Maestro, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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