apply_fix · Supabase Security MCP: Risk & Policy

WHAT IT DOES

What apply_fix does on Supabase Security

AI agents invoke apply_fix to trigger actions in Supabase Security. 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.

WHY IT NEEDS A POLICY

Why apply_fix needs a policy

This tool executes SQL statements against a live Supabase project to apply security fixes. While it has a confirmation gate and preview step, it runs arbitrary SQL with real side effects on a production database. The effects may or may not be reversible depending on the SQL applied, but the primary action is executing SQL — making Execute the appropriate category.

From the tool's definition ACTUALLY APPLY a fix SQL to the project. Requires confirm=true. Always run preview_fix first. Re-runs audit afterward to verify the finding is gone.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

apply_fix Rate-limited

apply_fix 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": {
    "apply_fix": {
      "limits": [
        {
          "counter": "apply_fix_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Supabase Security, so you can run agents against it safely.

FAQ

Questions about apply_fix

What does the apply_fix tool do? +

ACTUALLY APPLY a fix SQL to the project. Requires confirm=true. Always run preview_fix first. Re-runs audit afterward to verify the finding is gone. It is categorised as a Execute tool in the Supabase Security MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on apply_fix? +

Register the Supabase Security MCP server in PolicyLayer and add a rule for apply_fix: 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 Supabase Security. Nothing to install.

What risk level is apply_fix? +

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

Can I rate-limit apply_fix? +

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

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

apply_fix is provided by the Supabase Security MCP server (perufitlife/supabase-security-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.