[ MCP · FIELD NOTES ]
Five notes from "agents are becoming the buyer's interface" to "price the tool call" — the honest road from API to agent-ready platform.
The buyer's interface is quietly changing from a human clicking your dashboard to an agent deciding whether your API exists. If an agent can't call you, you're not losing a deal — you're not in the room where the deal happens.
You have a beautiful OpenAPI spec and a docs site humans love. An agent uses neither the way you think. Tool descriptions are the new landing page — and most APIs ship them by accident, if at all.
The demo takes an afternoon. Then come auth, keys, rate limits, versioning, observability and billing — and you realize you didn't build an MCP server, you started building a gateway you never staffed.
Three honest paths to an agent-callable API: generate it, operate it yourself, or run it as a managed layer. Each is right for a different team. Here's the fit test, without the vendor spin.
When agents are the ones calling, the unit of value becomes the tool call. Here's how to monetize agent access — per-call or subscription — and roll it out internal → enterprise → public without betting the company on day one.