AI agents invoke applyRun to trigger actions in Terraform Registry MCP Server. 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.
In Terraform, 'apply' executes planned infrastructure changes, provisioning or modifying real resources. The sibling tools 'createRun', 'cancelRun', 'lockWorkspace' confirm this is a Terraform Cloud/Enterprise workflow server. Applying a run can create, modify, or destroy infrastructure at scale, making it a high-severity Execute action.
From the tool's definition Tool name 'applyRun' — 'apply' in Terraform context means executing infrastructure changes against cloud/on-prem resources
Documented attack patterns abuse exactly the kind of access applyRun gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Terraform Registry MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for applyRun:
{
"version": "1",
"default": "deny",
"tools": {
"applyRun": {
"limits": [
{
"counter": "applyrun_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}applyRun 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.
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applyRun. It is categorised as a Execute tool in the Terraform Registry MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Terraform Registry MCP Server MCP server in PolicyLayer and add a rule for applyRun: 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 Terraform Registry MCP Server. Nothing to install.
applyRun is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the applyRun 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 applyRun. 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.
applyRun is provided by the Terraform Registry MCP Server MCP server (thrashr888/terraform-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 24 Terraform Registry MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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24 Terraform Registry MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.