I +1 this approach. We are doing similarly. Instead of providing MCP, we are simply providing API key and documentation. Folks are able to then just paste that link and use our service.
User will interact or build apps with simply text like: "Give me all the issues that are X, context: https://somedomain.com/llm.txt"
User will interact or build apps with simply text like: "Give me all the issues that are X, context: https://somedomain.com/llm.txt"
llm.txt will have all the API instructions