Filesystem-Based Context Engineering

The filesystem provides a single interface through which agents can flexibly store, retrieve, and update an effectively unlimited amount of context. This pattern addresses the fundamental constraint that context windows are limited while tasks often require more information than fits in a single window.

The core insight is that files enable dynamic context discovery: agents pull relevant context on demand rather than carrying everything in the context window. This contrasts with static context, which is always included regardless of relevance.

When to Use

Activate this skill when:

• Tool outputs are bloating the context window
• Agents need to persist state across long trajectories
• Sub-agents must share information without direct message passing
• Tasks require more context than fits in the window
• Building agents that learn and update their own instructions
• Implementing scratch pads for intermediate results
• Terminal outputs or logs need to be accessible to agents

Core Concepts

Context engineering can fail in four predictable ways. First, when the context an agent needs is not in the total available context. Second, when retrieved context fails to encapsulate needed context. Third, when retrieved context far exceeds needed context, wasting tokens and degrading performance. Fourth, when agents cannot discover niche information buried in many files.