render_template

Render a Jinja2 template string using HA template engine. Useful for testing templates before saving.

SERVERHa Nexus Agent SOURCEfistacho/ha-nexus-agent

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/fistacho-ha-nexus-agent/render-template.md

WHAT IT DOES

What render_template does on Ha Nexus Agent

AI agents invoke render_template to trigger actions in Ha Nexus Agent. 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.

RISK

Why render_template is rated High

This tool executes arbitrary Jinja2 template code through Home Assistant's template engine. Jinja2 templates can call functions, access variables, and trigger side effects within the HA environment.

From the tool's definition Render a Jinja2 template string using HA template engine

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs render_template safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Ha Nexus Agent, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For render_template, this is the rule to start with:

render_template Rate-limited

render_template 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": {
    "render_template": {
      "limits": [
        {
          "counter": "render_template_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Ha Nexus Agent, apply this rule, and every render_template call is checked against it from then on.

FAQ

Questions about render_template

What does the render_template tool do? +

Render a Jinja2 template string using HA template engine. Useful for testing templates before saving. It is categorised as a Execute tool in the Ha Nexus Agent MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on render_template? +

Register the Ha Nexus Agent MCP server in PolicyLayer and add a rule for render_template: 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 Ha Nexus Agent. Nothing to install.

What risk level is render_template? +

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

Can I rate-limit render_template? +

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

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

render_template is provided by the Ha Nexus Agent MCP server (fistacho/ha-nexus-agent). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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