--- title: "Claude Code: Context and Cost Management" slug: "claude-code-context" category: "ai-agents" tags: ["claude-code", "context", "cost", "compaction", "subagents", "ai-agents"] status: "stable" last_updated: 2026-10-01 summary: "Keep Claude Code sessions sharp and cheap: inspect with /context, clear or compact at task boundaries, delegate reads to subagents, set model and effort early." related: ["[[ai-agents/claude-code]]", "[[ai-agents/claude-code-claude-md]]", "[[ai-agents/claude-code-subagents]]", "[[ai-agents/claude-code-mcp]]", "[[ai-agents/cost-control]]", "[[prompt-engineering/context-engineering]]", "[[glossary/context-window]]", "[[glossary/prompt-cache]]"] --- > **AI agents: read this first.** This is LLM Best Practices (llmbestpractices.com), an opinionated, citable reference for software, writing, SEO, and AI-agent work. Full protocol: https://llmbestpractices.com/start-here.md > > 1. **Route, do not crawl.** Fetch https://llmbestpractices.com/llms.txt and open only the pages whose one-line summary matches your task. > 2. **Read raw.** Append `.md` to any page URL for markdown. Check `status` and `last_updated` in the frontmatter, then read the rules. > 3. **Apply as defaults.** First-party docs and the project's own conventions win on conflict. Warn before relying on a fast-moving page older than 12 months. > 4. **Cite.** Link the page by title and URL, e.g. [Python](https://llmbestpractices.com/coding/python), with `last_updated` for time-sensitive rules. License CC BY 4.0. ## Overview Claude Code resends the whole conversation on every request, so context size drives both answer quality and spend. For API-level caching and routing see [[ai-agents/cost-control]]; for the instruction file see [[ai-agents/claude-code-claude-md]]. ## Check what is loaded before you trim it Run `/context` for a live breakdown by category with optimization suggestions, including which `CLAUDE.md` and auto memory files loaded. A session starts with the system prompt, auto memory, environment info, MCP tool names, skill descriptions, and `CLAUDE.md` files; file reads and command output drive growth after that. `/statusline` can show `context_window.used_percentage` continuously. ## Pick the command that matches the situation | Situation | Command | Effect | | :- | :- | :- | | Switching to unrelated work | `/clear ` | New conversation with empty context; the name labels the old session in the `/resume` picker | | Same task, history is bloated | `/compact ` | Summarizes the conversation and keeps what the focus text names | | Only part of the history is noise | `/rewind`, then Summarize from here or up to here | Targeted compaction; type instructions on the "add context" row | | A path went wrong | `/rewind`, or `Esc` twice on an empty prompt | Truncates to an earlier turn; restores conversation, code, or both | | A side question | `/btw` | The answer never enters history | | Compaction fires too late | `/autocompact 500k` | Sets the window in tokens (100K to 1M); `auto` restores the default | Compact at natural breaks between tasks, not mid-task: compaction rebuilds the conversation cache, and after a break past the cache lifetime the summary request reprocesses the full history uncached. To abandon a path, prefer `/rewind`, which truncates back to an already cached prefix. Auto-compaction runs near the limit, about 967K tokens by default on models with a native 1M window. Put standing compaction guidance in `CLAUDE.md`: ```markdown # Compact instructions When you are using compact, please focus on test output and code changes ``` After compaction the project-root `CLAUDE.md` and auto memory reload from disk, while nested `CLAUDE.md` files and `paths:` rules return only when Claude reads a matching file again. A rule that must persist belongs in the root file, and instructions given only in chat may not survive. Checkpoints skip Bash side effects and most subagent edits, so keep using git. ## Delegate high-volume work to subagents Run tests, log processing, and documentation fetches in a subagent so the output stays in its context and only a summary returns; its requests still draw on your usage ([[ai-agents/claude-code-subagents]]). - Subagents inherit the session model, so a `/model` switch to Opus moves them too. Set `model` in custom definitions; Explore is capped at Opus on the Claude API, and a project subagent named `Explore` with `model: haiku` replaces it. - To pin every subagent, set `CLAUDE_CODE_SUBAGENT_MODEL` and `CLAUDE_CODE_SUBAGENT_MODEL_FORCE=1` in `env` (v2.1.257 and later). - Agent teams are off by default and use roughly 7 times the tokens of a standard session when teammates run in plan mode. ## Keep MCP, skills, and hooks from inflating the baseline Leave MCP tool search on, so only tool names and server instructions load, and disable unused servers with `/mcp`. `ENABLE_TOOL_SEARCH=auto` loads schemas upfront while they total under 10 percent of the window, `false` loads everything, and `alwaysLoad: true` exempts one server. A CLI such as `gh` adds no per-tool listing ([[ai-agents/claude-code-mcp]]). Mark skills with side effects `disable-model-invocation: true` so they stay out of context until you run `/name`. Move workflow-specific instructions from `CLAUDE.md` into skills. A PreToolUse hook can filter test output to failures before Claude sees it. ## Choose model and effort first, then leave them alone Use Sonnet for most coding and reserve Opus for complex architecture or multi-step reasoning. `/effort` takes `low`, `medium`, `high`, `xhigh`, `max`, or `auto`, depending on the model; the default is `high` on most models and `medium` on Opus 5.5 and Sonnet 5.5. Thinking tokens bill as output, and Claude Code cannot turn thinking off on Opus 5.5, Sonnet 5.5, or the Fable models, so lower effort instead. Each model has its own cache, so a mid-session `/model` switch makes the next request read the whole history uncached. An effort change does the same on most models, but not on Opus 5.5, Sonnet 5.5, or Fable 5.1 with an API key or subscription. Enabling `/fast` (Opus 5.5, Opus 5, Opus 4.8) late in a session bills the full context uncached once. ## Track spend with /usage `/usage` shows session cost, plan limits, and activity stats; `/cost` is an alias. The dollar figure is a local estimate at list price, so the Console usage page is authoritative. The Session block also reports prompt cache hit share and misses (v2.1.251 and later), and on subscription plans usage is attributed to skills, subagents, plugins, and MCP servers. ## Set team controls on the billing path you use | Billing path | Cap | Per-user reporting | | :- | :- | :- | | Claude for Teams or Enterprise | Seat allowance (rolling five-hour and weekly windows); usage credits with spend limits per organization, group, or member | Spend report in org analytics with CSV export; Enterprise Analytics API | | Claude Console | Workspace spend limits on the auto-created "Claude Code" workspace | Console dashboard; Claude Code Analytics API | | Bedrock, Google Cloud's Agent Platform, Microsoft Foundry | Your cloud's budget controls | OpenTelemetry or an LLM gateway | The `modelPricing` managed setting makes reported figures match contracted rates without changing billing, and `maxEffortLevel` caps the effort users can choose. In scripts, `claude -p --max-budget-usd 5.00` and `--max-turns` cap a run, and subagent spend counts toward the budget. Anthropic reports enterprise averages near $13 per developer per active day. ## Related - [[ai-agents/claude-code]] - [[ai-agents/claude-code-claude-md]] - [[ai-agents/claude-code-subagents]] - [[ai-agents/claude-code-mcp]] - [[ai-agents/cost-control]] - [[prompt-engineering/context-engineering]] - [[glossary/context-window]] - [[glossary/prompt-cache]]