create_table · Instant Db MCP: Risk & Policy

WHAT IT DOES

What create_table does on Instant Db

AI agents use create_table to create or update resources in Instant Db — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Instant Db environment.

WHY IT NEEDS A POLICY

Why create_table needs a policy

This is a Write operation because it creates/modifies data structures (schema) reversibly. It does not execute arbitrary code or delete data (which would be Destructive/Execute), but it does alter the database structure. Severity is medium because schema changes can impact application functionality and require careful planning, but the operation itself is reversible by dropping the table.

From the tool's definition The tool 'create_table' explicitly adds a new table to an existing database, which modifies the schema structure reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_table Rate-limited

create_table stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "create_table": {
      "limits": [
        {
          "counter": "create_table_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about create_table

What does the create_table tool do? +

Add a new table to an existing database. Use this to evolve a database schema without recreating it. Fails if the table already exists. It is categorised as a Write tool in the Instant Db MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_table? +

Register the Instant Db MCP server in PolicyLayer and add a rule for create_table: 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 Instant Db. Nothing to install.

What risk level is create_table? +

create_table is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit create_table? +

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

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

create_table is provided by the Instant Db MCP server (urbushey/mcp-db). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.