Intel / article

The New Rules of Context Engineering for Claude 5 Generation Models

Source: trq212
Author: trq212
Date: Published Jul 24, 2026

Terms in this piece · Glossary

system prompt — The standing instructions a model receives before any user input — defining its role, rules, tools, and tone for the whole conversation.
eval — A repeatable test for AI quality — a set of tasks plus scoring — used the way software teams use test suites, because model output is too variable to judge by eyeballing.
agent skill — A reusable instruction file that teaches an agent how to do one job well — the procedure, the tools, and what counts as done.
context window — The maximum amount of text a model can consider at once — its working memory for the current conversation or task.

Why it matters

If aggressive prompt reduction improves rather than degrades results, most existing project instructions are actively harmful.

Key quotes

“We removed over 80% of Claude Code’s system prompt for models like Claude Opus 5 and Claude Fable 5 with no measurable loss on our coding evaluations.”
trq212

“Overall, we found that we were overconstraining Claude Code, both through our system prompt and in our CLAUDE.md files and skills.”
trq212

“The number one rule for tool usage was to give Claude examples on how to use them. With our newest models, we’ve found that giving examples actually constrains them to a certain exploration space.”
trq212

“Some of our tools are ‘deferred loading,’ which means the agent must search for their full definitions using ToolSearch before using them. This allows us to have more tools (such as our Task tools) that don’t take up context until they’re needed.”
trq212

“Keep your CLAUDE.md lightweight and briefly describe what your repo is for, but spend most of the tokens on gotchas inside of the codebase.”
trq212

Read the source ↗claude.com