How to monetize Documentation Access MCP servers with x402.

A hallucinated API signature costs an agent a failed compile, a debugging loop, and thousands of wasted tokens. The Unreal Engine and Unity API documentation servers in this category pitch exactly that: accurate signatures that prevent hallucination. Preventing a multi-cent failure for one cent is the kind of trade an autonomous agent makes every time.

Maintaining that accuracy is also genuinely costly. Docs servers must ingest, index, and re-index documentation as frameworks ship new versions — Sceneview MCP covers an SDK across Android, iOS, and Web; augments-mcp-server tracks many frameworks at once. Freshness is the product, and freshness has an ongoing bill.

The unit of value is one resolved lookup — a question in, a relevant chunk of current documentation out. Straight retrieval prices well at the $0.01 minimum; the volume comes from agents calling on every task. Tools that synthesize rather than retrieve are worth more: migration guidance, feature checks against versions, or generated example code (the RevoGrid servers do all three) involve more compute and deliver more finished value, supporting $0.02–$0.10 per call.

Resist the urge to charge per token returned. Agents budget per call, and a docs server that returns a tight, token-efficient answer at a fixed price is more attractive than one with variable costs.

Your middleware answers an unpaid call with HTTP 402 and the price. The agent's wallet signs and retries, USDC settles on Base in about two seconds, and only then does your retrieval handler run. Settlement is final — no chargebacks — and the Ed25519-signed receipt gives the agent's operator a verifiable record of every lookup. For a high-frequency, low-price category like docs, the fact that the agent pays before your handler executes is what makes one-cent pricing viable: there's no billing reconciliation to amortize.

There are 84 documentation servers live on the Loomal marketplace. Claim yours by verifying GitHub ownership, then connect your hosted endpoint and set a price in the console. Minimum is $0.01 per call; repricing is one field, so you can test whether your lookups command more. Loomal's fee is 5% of settled transactions and is currently waived.

If you maintain docs for your own product — the RevoGrid and Ignite UI pattern — a paid MCP endpoint doubles as a support channel that funds itself.