Meredith Shubel writes that Vercel published `design.md`, a public prompt file that cut agent-generated design failures by 57% across 200+ agent runs, though none of the six tested pages was ship-ready. The system has three layers: a prompt encoding design judgment, a public stylesheet for mechanical layout rules, and an evaluation loop that converts human feedback into deterministic checks. A Slack-based agent (`design-agent`) consolidates weekly feedback from GitHub and Figma into proposed guidance updates.
- The comparison test used Codex with GPT-5.5: 39 failure instances with `design.md` versus 91 without.
- Vercel's first attempt to port its internal "product design" skill to a public prompt failed because subjective design language was interpreted differently by each model.
- Recurring complaint counts are tracked over time; if a fix doesn't reduce its count, the fix is flagged for refinement.
- The comparison test used Codex with GPT-5.5: 39 failure instances with `design.md` versus 91 without.
- Vercel's first attempt to port its internal "product design" skill to a public prompt failed because subjective design language was interpreted differently by each model.
- Recurring complaint counts are tracked over time; if a fix doesn't reduce its count, the fix is flagged for refinement.
Vercel has released Skills.sh, an open-source tool designed to provide AI agents with a standardized way to execute reusable actions, or skills, through the command line. The project introduces what Vercel describes as an open agent skills ecosystem, where developers can define, share, and run discrete operations that agents can invoke as part of their workflows.
Vercel's research shows that embedding a compressed 8KB docs index in AGENTS.md achieves a 100% pass rate for Next.js 16 API evaluations, while skills maxed out at 79%, even with explicit instructions. This suggests that passive context provision via AGENTS.md is more effective than active retrieval with skills for framework-specific knowledge in AI coding agents.
Vercel has open-sourced bash-tool, a Bash execution engine for AI agents, enabling them to run filesystem-based commands to retrieve context for model prompts. It allows agents to handle large local contexts without embedding entire files, by running shell-style operations like find, grep, and jq.
