generate_custom_javascript

THE RISK

High Risk

Why generate_custom_javascript needs a policy

This tool generates and likely injects/executes custom JavaScript code (A-Frame components) into web projects. Arbitrary JavaScript generation and execution carries high blast radius as malicious or erroneous code could compromise the web experience, exfiltrate data, or cause unintended behaviors. The warning about project type specificity further suggests it directly modifies runtime behavior.

From the tool's definition Generate A-Frame components for web-based projects

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

POLICY

How to control generate_custom_javascript

PolicyLayer is an MCP gateway — it sits between your AI agents and 8th Wall MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for generate_custom_javascript:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "generate_custom_javascript": {
      "limits": [
        {
          "counter": "generate_custom_javascript_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

generate_custom_javascript 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.

Create a free account and register 8th Wall MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More 8th Wall MCP Server tools

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All 64 8th Wall MCP Server tools →

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Go deeper

High-risk tools in 8th Wall MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about generate_custom_javascript

What does the generate_custom_javascript tool do? +

⚠️ WEB PROJECTS ONLY - NOT FOR DESKTOP! Generate A-Frame components for web-based projects. For Desktop (.expanse.json), use desktop_add_threejs_script instead!. It is categorised as a Execute tool in the 8th Wall MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on generate_custom_javascript? +

Register the 8th Wall MCP Server MCP server in PolicyLayer and add a rule for generate_custom_javascript: 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 8th Wall MCP Server. Nothing to install.

What risk level is generate_custom_javascript? +

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

Can I rate-limit generate_custom_javascript? +

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

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

generate_custom_javascript is provided by the 8th Wall MCP Server MCP server (superdwayne/8thwallmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every 8th Wall MCP Server tool call.

Start from 8th Wall MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →