Performs all built-in variable operations: create, list, remove, revert. The
AI agents call gtm_built_in_variable to permanently remove resources in Google Tag Manager MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
The tool includes 'remove' which irreversibly deletes built-in variables, and 'revert' which overwrites/undoes changes. Per severity rules, Destructive outranks Write and Read. Misuse by an AI agent could remove critical GTM built-in variables affecting tag/trigger/analytics behavior across a production GTM container, with potentially high blast radius.
From the tool's definition Performs all built-in variable operations: create, list, remove, revert
Documented attack patterns abuse exactly the kind of access gtm_built_in_variable gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Google Tag Manager MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for gtm_built_in_variable:
{
"version": "1",
"default": "deny",
"hide": [
"gtm_built_in_variable"
]
}gtm_built_in_variable disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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Performs all built-in variable operations: create, list, remove, revert. The. It is categorised as a Destructive tool in the Google Tag Manager MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Google Tag Manager MCP Server MCP server in PolicyLayer and add a rule for gtm_built_in_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 Google Tag Manager MCP Server. Nothing to install.
gtm_built_in_variable is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the gtm_built_in_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.
Set action: deny in the PolicyLayer policy for gtm_built_in_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.
gtm_built_in_variable is provided by the Google Tag Manager MCP Server MCP server (stape-io/google-tag-manager-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 18 Google Tag Manager MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
18 Google Tag Manager MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.