What happens to your agent when the team renames users to accounts, and why the tool name you picked six months ago decides whether anything breaks

TL;DR: I have shipped MCP servers where the tool names were a thin shell over the underlying REST API, and I have shipped servers where the names came from the domain model instead. The domain-named ones survived backend refactors with close to zero churn. The pass-through ones broke every time someone renamed a table or split a service. After ranking six naming patterns by two axes (how well a name survives a refactor of the system underneath it, and how cleanly the model can pick the right tool), my house pick is ubiquitous-language naming inside a bounded-context prefix, with Pydantic discriminated-union return types doing the schema work. The one-line version of my opinion: Domain-Driven Design plus tool-use schemas is the production fix for agents.…