PREFLIGHT — URL Routing for AI Agents

Name: PREFLIGHT — URL Routing for AI Agents
Author: GSterlingPress

by GSterlingPressversion 0.7.6i★ –iRuns in the cloud

Registry nameio.github.GSterlingPress/preflight

Install

Overview

Description from the maker (original English)

Choose HTTP, browser, machine endpoint, or avoid before an agent visits an unfamiliar URL.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs in the cloud
Transport: Streamable HTTP
Category: Web & browsers

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on the maker’s server: what you ask it goes through their server.
The registry lists no key to fill in.

You need

Runs in the cloudNothing to install; it connects over the internet

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Works in Claude on the web, desktop and mobile:

Open Settings → Connectors
Press Add custom connector
Paste the address below and press Add
If it asks you to sign in, sign in with the maker

https://preflight-api-production-01a2.up.railway.app/mcp

Run this in your terminal

claude mcp add --transport http preflight https://preflight-api-production-01a2.up.railway.app/mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "preflight": {
      "url": "https://preflight-api-production-01a2.up.railway.app/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "preflight": {
      "type": "http",
      "url": "https://preflight-api-production-01a2.up.railway.app/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

ChatGPT connects only to servers on the internet:

Open ChatGPT on the web → Settings → Connectors (Apps)
Press Create or Add (some plans need Developer mode under Advanced first)
Paste the address below, give it a name and save
If it asks you to sign in, sign in with the maker

https://preflight-api-production-01a2.up.railway.app/mcp

Menu names can differ slightly by plan and over time.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

We have not read this server’s tool list yet; we check endpoints in rotation.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account GSterlingPress, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
… Not checked yet
Endpoint responds
Not checked yet; we check endpoints in rotation
… Not checked yet
Sign-in with OAuth
Not checked yet; we check endpoints in rotation
… Not checked yet
No hidden instructions in tool descriptions
Not checked yet; we read the tool list when we check the endpoint

Compared with others in Web & browsersi

More stars than 0% of the other 880 servers in this category
Published to the registry more recently than 39% of the other 880 servers in this category
Basic checks equal to or better than 100% of the other 880 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is PREFLIGHT — URL Routing for AI Agents safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.7.6) reached the registry 2 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.

What can I use instead?

In the same category: Browser Use, Chrome DevTools MCP, MCP Server Browser

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Browser Use

by browser-use

Lets AI do web tasks for you, such as filling forms, searching and extracting data, in the maker’s cloud browsers or on your computer.

Computer or cloud★ 120,087MITUpdated 17 days ago

Install

Chrome DevTools MCP

by ChromeDevTools

Lets AI use Chrome’s developer tools to inspect pages, find what makes them slow and spot errors. Made by the Chrome DevTools team.

Runs on your computer★ 54,821Apache-2.0Updated 15 days ago

Install

MCP Server Browser

by bytedance

MCP server for browser use access

Runs on your computer★ 39,550Apache-2.0Updated 14 months ago

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

PREFLIGHT

Before your AI agent visits a URL, ask us how to get there.

PREFLIGHT is routing intelligence for browser, research and shopping agents. Given a URL, it recommends the cheapest likely route to try first: HTTP, BROWSER, MACHINE_ENDPOINT, or AVOID.

The long-term product is a machine map of the web: not *what is on the web*, but *how should a machine interact with this destination?*

Live service

Base URL:

https://preflight-api-production-01a2.up.railway.app

REST — use the actual URL your agent is about to visit:

GET /v1/check?url=<encoded-actual-destination-url>

For example, if your agent is about to inspect a product, documentation page, article, booking page, or SaaS site, pass that real destination to PREFLIGHT first. example.com is only a documentation placeholder and should not be used when a real task URL exists.

Remote MCP:

https://preflight-api-production-01a2.up.railway.app/mcp

The MCP server exposes two tools:

preflight_check — call this before fetching or browser-rendering an unfamiliar real URL.
preflight_feedback — report whether the chosen route worked so PREFLIGHT can improve future recommendations.

Example tool intent:

Before opening the URL from my current task, use PREFLIGHT to decide whether ordinary HTTP, a browser, a machine-readable endpoint, or avoidance is the best first route.

Why an agent should call PREFLIGHT

Fetching first can be wasteful. A destination may be directly readable over HTTP, require browser rendering, expose a smaller machine endpoint, block automation, require authentication/payment, or carry access signals that make a fetch undesirable. PREFLIGHT tries to answer that routing question before the expensive step.

Responses combine direct probe signals, cached domain knowledge, and sufficiently strong observed route feedback. They can include status, redirects, robots/access hints, estimated token size, JavaScript-shell hints, structured-data signals, machine endpoints, latency, confidence, cache age, and learned route evidence.

Feedback loop

POST /v1/feedback

Content-Type: application/json Authorization: Bearer # when protection is enabled

"url": "https://merchant.example/product/123", "route": "BROWSER", "outcome": "success", "latencyMs": 840 }

PREFLIGHT stores aggregated success/failure evidence rather than page content or user identities. URL-level learning requires at least 5 samples at 80% success; domain-level learning requires at least 10 samples at 85% success. Feedback never overrides a current AVOID decision from live safety/access/robots signals.

Agent discovery

AGENTS.md tells coding/AI agents exactly when to use PREFLIGHT.
llms.txt gives LLMs a compact machine-readable explanation, live endpoints, and usage rule.
openapi.json exposes REST operations in OpenAPI 3.1 format for tool importers and generated clients.
mcp.json contains a generic remote MCP client configuration.
docs/AGENT-INTEGRATIONS.md contains copy/paste integration patterns for browser, research, shopping, coding, MCP, and REST agents.
server.json contains official MCP Registry metadata for the public Streamable HTTP server.
/mcp supports MCP initialize, initialized notification, ping, tools/list, and tools/call.
The ordinary REST endpoint remains available for clients that do not use MCP.

Search/discovery concepts: AI agent URL routing, browser-agent preflight, choose HTTP vs browser, machine-readable endpoint discovery, reduce agent browsing tokens, agent web routing, pre-fetch routing intelligence, AI browser cost reduction, route before crawl, agent URL access intelligence.

Public deployment

GET /ready verifies the data directory is writable. Railway deployments use /data; mount a persistent volume there when long-term feedback persistence is required. PREFLIGHT_FEEDBACK_KEY optionally bearer-protects feedback writes while keeping route checks public. npm run smoke:live exercises the public route/feedback cycle.

Real-world benchmark

benchmarks/sites.json contains a cross-category live corpus. Run npm run benchmark. The scheduled benchmark records route, status, latency, token estimate and machine endpoints and preserves machine-readable reports for trend analysis.

Safety boundary

PREFLIGHT blocks localhost, private/link-local network addresses, credential-bearing URLs, non-HTTP protocols, and unsafe redirect destinations. Endpoint discovery and negotiated probes go through the same SSRF-safe fetch layer. MCP validates browser Origins, and route feedback cannot relax an active AVOID result.

Run locally

Requires Node.js 20+.

npm test

npm start

Product boundary

PREFLIGHT is not a crawler, browser farm, search engine or site-owner audit tool. Its job is narrower:

Real URL in → cheapest reliable machine route out.

PREFLIGHT — URL Routing for AI Agents

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Web & browsersi

Common questions

Alternatives

Browser Use

Chrome DevTools MCP

MCP Server Browser

README from the maker

PREFLIGHT

Live service

Why an agent should call PREFLIGHT

Feedback loop

Agent discovery

Public deployment

Real-world benchmark

Safety boundary

Run locally

Product boundary