Katelyn Lesse – Evolving Claude APIs for Agents, Anthropic

Summary

• Caitlyn Lesse (Anthropic Claude developer platform lead) frames the Claude API evolution around three pillars: harness Claude's capabilities, manage its context window, and give Claude a computer.
• Capabilities surface as API features: extended thinking with a token budget, plus tool use (built-in like web search and custom tools with name/description/input schema).
• Context management spans MCP for external tools, a clientside-filesystem memory tool, and context-editing that clears stale tool results; combining memory + context editing yielded a 39% bump on internal evals, with up to 1M-token windows on some models.
• 'Give Claude a computer' — Anthropic launched Claude Code on web/mobile with their code execution tool: sandboxed container orchestration handled server-side so users don't manage infra.
• Claude is being trained to be aware of how much of its context window remains and to plan accordingly.