context-engineering

Context engineering — the window is a budget, spend it well

Every token in the context window costs money, latency, and attention (more noise = worse answers). Context engineering is deciding, deliberately, what earns a place in the window — and routing the rest elsewhere.

The disciplines

1. Keep instructions small and prefix-stable. A lean CLAUDE.md / system prompt beats a kitchen sink. Prompt caching rewards a stable prefix: put the unchanging stuff first and don't reorder it — a change near the top invalidates the cache for everything after it. (Pairs with workspace-architect.)
2. Retrieve, don't dump. Pull the few relevant files / snippets; never paste a whole repo or doc. Use a ranked map (repo-map) or a code graph (CodeGraph) to find the load-bearing few. (Pairs with repo-map.)
3. Fresh docs at query time, not pasted. Stale pasted docs cause hallucinated APIs; fetch version-correct docs on demand with a docs MCP (Context7) instead.
4. Compress tool output before it lands. Logs, git status, test output, find — pipe them through a compressor (RTK) or summarize before feeding them in; raw command spew is the quiet token killer.
5. Audit your MCP servers. Every connected MCP injects its tool definitions into every request. Keep only the ones this project uses — each unused server is a permanent context tax.
6. Stop documentation inflation. Instruction files grow unbounded if you let them. Trim ruthlessly; link to detail instead of inlining it; one fact in one place.
7. Hand off cleanly across sessions. For long work, take a clean break with a short handoff note so the next session restarts from a compact summary, not a giant transcript. (Pairs with compactor.)
8. Measure tokens like an infra cost. Right-size the model per task (model-router — Haiku scouts, Opus for the hard calls), trim output (caveman / token-economy), and watch usage (Tokscale) instead of guessing. What you don't measure, you overspend.

The quick audit

Run it when a session feels expensive or the model is losing the thread:

• What's in the window that isn't earning its tokens? (a bloated CLAUDE.md, pasted docs, raw logs, unused MCPs)
• Could a retrieval step replace a dump? Could a cheaper model do this turn? Is the prefix stable enough to cache?
• Fix the biggest leak first; re-measure. Treat it like profiling, not vibes.

Where SKULL already helps

token-economy (best output per token), repo-map (ranked retrieval), compactor (session handoffs), model-router (right model per task), workspace-architect (a lean .claude/). The external power-ups — Context7, CodeGraph, RTK, Tokscale, caveman — are in docs/ECOSYSTEM.md.

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Credits: the "15 ways to stop burning tokens" context-engineering playbook (devwithmj on Medium). We re-implement the ideas and point you at the tools. See docs/ECOSYSTEM.md.