Simon Willison's 2025 LLM review: coding agents as the year's most impactful development¶
Insight: Willison identifies Claude Code's quiet February 2025 release as "the most impactful event of 2025" in the entire LLM space. Every major lab released a CLI coding agent (Claude Code, Codex CLI, Gemini CLI, Qwen Code, Mistral Vibe). Claude Code reached $1B run-rate revenue by December — unprecedented for a CLI tool. The "asynchronous coding agent" category (Claude Code for web, Codex cloud) enables YOLO-mode by default since there's no personal computer to damage.
Detail: Willison frames MCP as "(only?) year of MCP" suggesting uncertainty about its longevity. He reiterates the "lethal trifecta" security concern. He describes the "Normalization of Deviance" phenomenon — repeated AI tool usage without negative consequences leads to accepting risky behavior as normal, analogizing to the Challenger disaster's faulty O-ring. The outcome-driven vs. process-driven split in developers is a defining tension for 2026.
Sources
- Simon Willison — "2025: The year in LLMs" (2025-12-31)
Related: existing entry "MCP security concerns" in external/mcp.md — CORROBORATES