Integrate the gate in your own code

Pick your runtime:

# TypeScript
npm i @mcp-index/sdk

# Python
pip install mcpindex-gate   # or: uv add mcpindex-gate

Wrap the session you already authenticated. The wrapper reuses its transport, so list_tools / call_tool stay drop-in and no credentials pass through mcpindex.

// TypeScript
import { wrap, PreflightPin } from "@mcp-index/sdk";

const guarded = wrap(session, { pin: new PreflightPin(), serverId: "your-server" });
// use guarded.list_tools() / guarded.call_tool(...) exactly as before

# Python
from mcpindex_gate import wrap, PreflightPin

session = wrap(session, pin=PreflightPin(), server_id="your-server")

On a breaking contract change the gate holds before the tool runs, so the wrapped tool is never called on a hold. By default it surfaces the hold; pass a handler if you would rather intercept it.

// TypeScript - the guarded call REJECTS with a PreflightHold by default,
// or route it to a handler:
const guarded = wrap(session, {
  pin: new PreflightPin(),
  serverId: "your-server",
  onHold: (verdict) => { /* log, prompt a human, or re-pin */ },
});

# Python - raises PreflightHold by default, or pass on_hold:
session = wrap(session, pin=PreflightPin(), server_id="your-server",
               on_hold=lambda verdict: ...)

A persisted baseline means drift that lands while your agent is offline is still caught on the next call. How you persist depends on the runtime, and this is the one place the two SDKs differ:

• Python: pass a path. PreflightPin(path="~/.mcpindex/pins/your-server.json") loads a prior baseline on start and writes updates atomically.
• TypeScript: PreflightPin is in-memory only, it takes no path, so a fresh process re-pins from scratch. For durable pins in a TypeScript setup, run the tool behind the standalone gate/proxy instead, which keeps its own on-disk pin store.

If you only run inside a long-lived process, the in-memory pin is fine either way.

The blast-radius grade is on by default alongside the pin, labeling each call's action, reversibility, and egress. Separately, the advisory directory HTTP API (preflight, trust, screen) covers discovery and pre-wire screening, but that is not the in-path gate: the contract pin and diff always run locally.