Anthropic’s sharpening the blueprint for building tools that play nice with LLM agents. Their Model Context Protocol (MCP) leans hard into three pillars: test in loops, design for humans, format like context matters—because it does.

They co-develop tools with agents like Claude Code. That means prototyping side-by-side, pressure-testing with structured evals, and prompt-wrangling tool specs until Claude stops hallucinating and starts calling the right APIs.

Big shift: You're no longer building for checkbox-clicking APIs. You're building for opinionated, non-deterministic models with vibes. Forget rigid abstractions. Focus on flexible scaffolding, tight eval cycles, and giving the model what it needs, when it needs it.