Context Budgeting Skill

Context Budgeting

Every token in context is a cost you pay every turn. This skill is the discipline that keeps long sessions cheap and coherent.

Token arithmetic

Rough budget on a 200K-context model:

| Consumer | Typical | Budget | |---|---|---| | System prompt + CLAUDE.md | 3–8 K | ≤ 10 K | | Skills frontmatter (all active) | 2–6 K | ≤ 8 K | | MCP tool schemas (passive) | 5–25 K | ≤ 15 K | | Hook definitions | <1 K | <1 K | | Conversation history | variable | ~120 K | | Working headroom | — | ≥ 20 K |

If passive context (everything before conversation history) exceeds 30 K, optimize.

Three-tier loading (skill-creator canonical)

| Tier | What | Size | Loaded | |---|---|---|---| | 1 — Frontmatter | name + description | ~50 tokens | always | | 2 — Body | SKILL.md after frontmatter | ≤ 500 lines | on activation | | 3 — References | references/*.md, MCP KB artifacts | unlimited | on demand |

Rule: if content doesn't change Claude's behavior every session, it belongs in tier 3.

/compact strategy

/compact condenses conversation history when it's filling up. It does NOT touch system prompt, CLAUDE.md, or skills.

When to /compact:

Conversation > 60 K tokens.
About to start a new phase (logical break).
Many long tool outputs in history.

When NOT to /compact:

Mid-debugging where specific earlier context matters.
Right before an important decision — the lost nuance might bite.
After a fresh /clear (nothing to compact).

Anchor preservation: before /compact, save anything you'd lose to engram via mem_save. After compact, the post-compact-context-restoration hook re-loads memory rules and recent context.

/clear vs /compact

| Command | What it does | |---|---| | /compact | Summarize history, keep system prompt + CLAUDE.md | | /clear | Wipe everything including CLAUDE.md — fresh session |

Use /clear between unrelated tasks. Use /compact mid-task.

Subagent delegation for context pressure

When a single subtask would consume too much context (e.g. scanning a huge codebase), delegate to a subagent. The agent gets a fresh window; you only see its report.

Agent({
  description: "Inventory all API endpoints",
  prompt: "Scan src/api/ recursively, list every route with method, auth requirement, and response schema. Report under 500 words."
})

Net: the scan consumes agent tokens; your session only pays for the 500-word summary.

Session analytics

Track cost patterns:

| Metric | Target | |---|---| | Passive context (pre-conversation) | ≤ 30 K | | Cost per turn | ≤ $0.05 (Sonnet), ≤ $0.15 (Opus) | | Tools loaded but never called per session | 0 (prune unused MCPs) | | /compact frequency | every 20–30 exchanges on long sessions | | Subagent delegation rate | ~1 per 5 substantive turns |

Session analytics isn't automatic — periodically review what's consuming tokens and trim.

MCP delegation

| Need | Tool | |---|---| | Settings schema for compact config | cc_docs_settings_schema | | Compact/budget troubleshooting | cc_docs_troubleshoot("context") | | Model cost for budgeting | cc_docs_model_recommend(task, budget) |

Anti-patterns

Loading every skill body "just in case" → tier-2 explosion.
Massive CLAUDE.md with all conventions inline → routing fails + budget bloat.
Never compacting → session hits wall, Claude forgets the plan.
Compacting mid-critical-reasoning → loses the thread.
Global MCPs for project-specific work → 15 K tokens for tools you never call.

Reference

compact-strategies.md — when to compact, anchor checklist, post-compact recovery

Agent Skills: Context Budgeting

Install this agent skill to your local

Skill Files