The company trimmed its system prompt by roughly 66%, dynamically loads less frequently needed built-in tools, improved prompt-cache placement, and reduced line-number overhead in file reads.
Cursor says it A/B tested tool-context configurations against token use, cost, latency, tool-call errors, and overall agent usage. It retained common reading, search, editing, and shell tools in static context while moving other definitions to dynamic loading. The post reports a 60% reduction in static-context tool-description tokens and a 20% lower cold-cache-miss rate.