I built Manifold, an operation-first foundation for .NET. The idea is simple: define an operation once, then generate fast CLI and MCP surfaces from that single definition. I made it because I kept running into the same problem in real projects: the same capability needed to be exposed through multiple developer-facing surfaces, but the definitions, bindings, and runtime wiring kept drifting apart over time. Manifold focuses on: one handwritten operation definition as the source of truth source-generator-first design generated CLI bindings generated MCP tool metadata and invocation samples for CLI, MCP stdio, and MCP Streamable HTTP Repo: https://github.com/Garume/Manifold Release: https://github.com/Garume/Manifold/releases/tag/v1.0.0 Wiki: https://github.com/Garume/Manifold/wiki I’d especially love feedback on whether this API shape feels natural for .NET, and whether a foundation like this is useful for MCP-oriented tooling.