From listed to earning
the MCP server seller journey.
Many servers in Mailgent Index started as an unclaimed stub the crawler found, then became a priced, earning listing in an afternoon. Here's the full path from 'indexed' to 'earning' — with a worked example — and why each step is smaller than you'd expect.
The journey from 'I built an MCP server' to 'my MCP server earns money' is usually imagined as a cliff: pick a billing provider, build metering, handle invoices, reconcile payments, chase the ones that fail. On Mailgent Index it's a ramp — most of the work is done the moment you list, and the rest is moving a single number.
The reason is that payment infrastructure isn't a later step you bolt on. It's installed when you integrate the SDK. From then on, the only ongoing decision is the price, and that's a field you can move anytime. This page walks the whole path stage by stage, then traces one server through it as a concrete example.
Stage 0 — Indexed (you may already be here)
Mailgent continuously crawls public MCP servers from GitHub, npm, and the official MCP registry. For each one it finds, it creates an unclaimed stub in the index — pulling the name, description, repository link, license, and the tools the server exposes from the public metadata.
If your server is public, there's a good chance a stub already exists. That stub is discoverable but inert: it can't take payment until someone claims it and integrates the SDK. Claiming is how you take ownership, and it costs nothing.
Stage 1 — Claimed and integrated
Claim the stub (or create a fresh listing), then integrate @mailgent/sdk and wrap your tools with requirePayment. Your handler logic is unchanged — the wrapper only adds the price and the payment handshake.
This is the one real engineering step, and it's small: install a package, wrap each tool, set a price. Most builders do it in an afternoon.
import { requirePayment } from "@mailgent/sdk";
server.tool(
"extract_pdf",
requirePayment({ amount: "0.02" }, async ({ url }) => extract(url)),
);Stage 2 — Live and discoverable
Once listed, your server is x402-ready: agents can find it in the index, read its price, and call-and-pay in one transaction. Price near the floor ($0.01–$0.02) to start. A low entry price is the cheapest way to attract your first callers and generate the usage data that tells you what the tool is actually worth.
Every call from here on settles in USDC on Base and produces a signed receipt, so you have real revenue and a clean audit trail from day one.
Stage 3 — Earning more
As usage proves the tool's value, raise the price. Change the amount from $0.02 to whatever a call is worth — $0.05, $0.10, more. The agents that value the tool keep calling and pay the higher rate; price-sensitive ones drop off. There's no contract and no minimum commitment, and if you raise too far you simply lower the number back down.
The market gives you feedback in call volume within hours, not quarters — so you can tune price against real demand instead of guessing once and living with it.
A worked example
Take a PDF-extraction server. The builder claims the crawler's stub, wraps the extract tool, and lists at $0.02 a call. In the first week agents discover it through the index and it handles 4,000 calls — $80 of revenue and, more importantly, proof that agents want it.
Seeing steady demand, the builder raises the price to $0.05. Volume dips slightly to 18,000 calls the next month but revenue climbs to $900. The only 'work' between $80 and $900 was changing one number twice. That's the shape of the ramp: integrate once, then let price and usage find each other.
Why the ramp is short
Repricing is one field, not a new integration — listing is the SDK distribution mechanism, so listing and integrating happen together. Because every call already carries a signed receipt and on-chain settlement, you get an audit trail for nothing, which is exactly what you'll want the day a buyer or a finance team asks for one.
And because agents pay from a wallet, you never issue API keys, manage a free tier of access, or reconcile invoices. The payment is the authorization, and it clears in seconds.
FAQ
How long does it take to go live?
Integrating the SDK and listing is roughly an afternoon. Changing your price afterward is a one-line edit you can ship in minutes.
What's the lowest I can price a call?
$0.01. Starting at or near the floor is a common way to attract early callers; you raise the price as the tool proves its value.
What does the crawler pull into a stub?
Public metadata only — name, description, repository link, license, and the tools your server exposes. The stub is discoverable but can't take payment until you claim it and integrate the SDK.
What if my server is already listed as a stub?
Claim it. Claiming transfers ownership to you so you can integrate the SDK, control the listing, and set your price. It's free.
Will raising my price lose my callers?
Some price-sensitive agents drop off; the ones that value the tool keep paying. You see the effect in call volume within hours, and you can lower the price again if you overshot.
How do I get paid?
Settlement is instant in USDC on Base. Cash out to any wallet you control, or use the smart wallet Mailgent provisions for your project at signup.
Related reading
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Last updated: 2026-05-27