run_select · Hospital MCP Server MCP: Risk & Policy

WHAT IT DOES

What run_select does on Hospital MCP Server

AI agents invoke run_select to trigger actions in Hospital 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.

WHY IT NEEDS A POLICY

Why run_select needs a policy

Although constrained to SELECT (read-only), this tool executes arbitrary SQL against a sensitive hospital database containing PII, medical records, and billing data. Even read-only SQL execution can expose highly sensitive patient data at scale if misused.

From the tool's definition 'Executes a read-only SQL SELECT query against the database' — the tool runs SQL statements against a live hospital database

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

run_select Rate-limited

run_select 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": {
    "run_select": {
      "limits": [
        {
          "counter": "run_select_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 Hospital MCP Server, so you can run agents against it safely.

FAQ

Questions about run_select

What does the run_select tool do? +

Executes a read-only SQL SELECT query against the database and returns the results. It is categorised as a Execute tool in the Hospital 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 run_select? +

Register the Hospital MCP Server MCP server in PolicyLayer and add a rule for run_select: 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 Hospital MCP Server. Nothing to install.

What risk level is run_select? +

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

Can I rate-limit run_select? +

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

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

run_select is provided by the Hospital MCP Server MCP server (sheshugit/mcp_postgres). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.