Claude Code status line token usage: the status line is free, agent_summary and startup context are not

Claude Code's custom status line consumes zero API tokens because it runs as a local script, but the `agent_summary` call that labels background agents costs between 2% and 26% of Claude Code spend, according to measurements from Anthropic, Flamerix AI and individual users. Flamerix AI measured `agent_summary` at 16.4% of one organization's weekly Claude Code spend, while Anthropic puts it at about 2% across its telemetry users and subagent-heavy sessions report 8% to 26%; the behavior has been on by default for interactive background agents since version 2.1.232 (13 August 2026), a change the changelog for that version does not mention. The author's own setup carried 43,394 tokens of startup context into a one-word reply on Claude Code 2.1.316, measured on 1 November 2026, with startup context ranging from 2,102 to 64,887 tokens per request.

Claude Code status line token usage: the status line is free, agent summary and startup context are not The Claude Code https://stackness.dev/tools/claude-code status line uses no model tokens: the docs https://code.claude.com/docs/en/statusline say it "runs locally and does not consume API tokens". The cost behind this week's "3-word status line" headline is agent summary , a separate call that labels each working background agent in the agents panel. Flamerix AI measured it at 16.4% of one organisation's weekly Claude Code spend. Anthropic puts it at about 2% of cost across its telemetry users, and users who measured their own subagent-heavy sessions report 8% to 26% of spend or tokens. Before any of that, my own setup carried 43,394 tokens of context into a one-word reply on Claude Code 2.1.316, measured on 1 November 2026. Claude Code status line token usage is zero; three other things cost tokens Claude Code's custom status line costs no tokens because it is a local script: Claude Code pipes session JSON to it on stdin and prints whatever it returns. Three things do cost tokens before or beside your instructions: the startup context sent with every request, agent summary calls for background agents, and side calls such as session titles, recaps and prompt suggestions. The table puts a measured number on each. | Overhead | When it runs | Measured size | Source | |---|---|---|---| | Status line script | Each new message, 300 ms debounce | 0 tokens | Statusline docs https://code.claude.com/docs/en/statusline | | Startup context | Every request, mostly as cache reads | 2,102 to 64,887 tokens per request | My runs, 1 November 2026 | | agent summary | About every 30 s per working background agent | 2% to 24% of spend, up to 26% of tokens | Anthropic, Flamerix, users | | Session title | First prompt of an interactive session | One small Haiku-class request | Sessions docs https://code.claude.com/docs/en/sessions | | Recap, prompt suggestions, idle compaction | Idle time, after each reply, after an hour away | Suggestions: 2.5% of weighted tokens in one session https://github.com/anthropics/claude-code/issues/86879 ; recap and idle compaction unmeasured | Costs docs https://code.claude.com/docs/en/costs | agent summary sends a background agent's transcript every 30 seconds agent summary is the call that writes the 3-5 word label next to each background subagent in Claude Code's agents panel. About every 30 seconds, for each background agent still working, Claude Code forks that agent's conversation and sends it to the agent's own model with one instruction: describe the most recent action in 3-5 words. An Opus subagent is summarised by Opus, a Haiku subagent by Haiku. The Flamerix gist https://gist.github.com/flamerix-ai/c3905705cc4205e5de3011fa2e74efce , first committed on 28 October and on the Hacker News front page https://news.ycombinator.com/item?id=50284255 the next day with 584 points, says the behaviour has been on by default for interactive background agents since 2.1.232 13 August 2026 ; the changelog https://github.com/anthropics/claude-code/blob/main/CHANGELOG.md for that version does not mention it. Headless claude -p runs skip it unless the undocumented CLAUDE CODE AGENT PROGRESS SUMMARIES is set. Since 2.1.128 a tick is skipped when the transcript has not changed. Most of each call is a cache read, $0.20 per million tokens on Opus 5.5 against $4 uncached pricing https://platform.claude.com/docs/en/about-claude/pricing . A 100,000-token transcript summarised 120 times an hour is 12 million cache-read tokens: $2.40 per agent-hour on Opus 5.5, and $0.60 on Haiku 5.5, whose prompts above 100,000 tokens cost five times more. A call that misses the cache pays the uncached rate, about 20 times as much, and Flamerix found the 2% of calls that missed carried over a third of the cost. The code in my installed 2.1.316 still runs on a 30,000 ms timer. A server-side flag picks between the default full mode, which forks the whole transcript, and a short mode that sends about 2,000 tokens of notes to a writer model. That matches Anthropic's reply https://news.ycombinator.com/item?id=50284699 on Hacker News, which says a fix for cache-missing summaries shipped in 2.1.311 and a cheaper notes mode is in the works; neither is in the changelog. I repeated the gist's controlled test on 2.1.316: one Haiku 5.5 background subagent running eight 20-second sleep commands, with summaries forced on, then left at the headless default. The first run made 5 summary calls, 31 seconds apart, each reading about 35,000 tokens; the second made none. The five calls cost about $0.0037 at list price, 20% of their run's $0.018, and the first one missed the cache. Measured agent summary shares run from 2% to 24% of spend The share of Claude Code spend that goes to agent summary depends on how many background agents a session runs. Anthropic's 2% averages every telemetry user, including people who never start a background agent; the 16.4% and the user numbers come from teams running many long subagents, who are the ones who went looking. All figures are self-reported, and only Anthropic's covers more than one team. | Who | Version | Sample | Share | |---|---|---|---| | Anthropic edwinarbus https://news.ycombinator.com/item?id=50284699 | not stated | Telemetry users, week before 29 Oct | ~2% of cost, under 4% of requests; ~6% of cost in the terminal | | Flamerix AI https://gist.github.com/flamerix-ai/c3905705cc4205e5de3011fa2e74efce | to 2.1.301 | One organisation, one week, size not given | 16.4% of estimated spend, 19.7% of requests | | rflcrz https://github.com/anthropics/claude-code/issues/86879 | 2.1.233 | 1 session, 4 h, 27 subagents | 18.0% of weighted tokens, 22.7% of requests | | sylvain-artois https://github.com/anthropics/claude-code/issues/86879 issuecomment-5730931355 | 2.1.276 | 1 session, 1 h 45 min, 4 subagents | 26% of cache-read tokens | | chrisvaillancourt https://github.com/anthropics/claude-code/issues/86879 issuecomment-6509552460 | 2.1.312 | 30 days, 129 sessions | ~10% of spend, 24% in a 40-agent session | | jakozaur https://news.ycombinator.com/item?id=50284683 | not stated | Own sessions | "~8% at most" | On a subscription none of this is a bill; it comes out of the five-hour and weekly limits. A one-word reply carried 2,102 to 64,887 tokens on my machine Claude Code's startup context is the system prompt, tool definitions, CLAUDE.md files, memory, the skills listing and MCP server instructions, sent with every request. I asked Claude Code 2.1.316 to reply "OK" in six configurations with claude -p --output-format json --model sonnet and added the input, cache-write and cache-read counts it reported. | Configuration | Context tokens | First-call cost Sonnet 5.5 | |---|---|---| | --safe-mode --tools "" : no tools, no customisations | 2,102 | $0.006 | | --safe-mode : built-in tools only | 16,222 | $0.021 | | Full setup, MCP servers and skills off | 34,420 | $0.061 | | Full setup, no MCP servers --strict-mcp-config | 39,144 | $0.102 | | Full setup in an empty folder | 43,394 | $0.129 | | Full setup in the Stackness repository | 64,887 | $0.215 | Built-in tool definitions are the biggest block at 14,120 tokens. My 20 MCP servers add only about 4,250, because Claude Code defers MCP tool definitions https://code.claude.com/docs/en/costs until a tool is used; the skills listing adds about 4,700 and the Stackness CLAUDE.md and project memory 21,493. After the first request it is all cache reads: 43,394 tokens cost about $0.004 a request on Sonnet 5.5 and $0.009 on Opus 5.5. Measure your own overhead with /context, OpenTelemetry and a debug log Claude Code offers three ways to see what it sends besides your words, and transcript readers such as ccusage https://stackness.dev/tools/ccusage are not one of them: summary forks are never written to the session files under ~/.claude/projects/ , as issue 104358 https://github.com/anthropics/claude-code/issues/104358 documents. /context shows the startup context by category, and /context all lists each item. claude -p --output-format json prints usage and modelUsage ; in my test, modelUsage included the summary calls. OpenTelemetry https://stackness.dev/tools/opentelemetry is the only documented way to see each agent summary request on its own: group the claude code.api request events by query source . Without a collector, the debug log works, though its lines are internal and can change: claude --debug-file /tmp/cc-debug.log grep -c '\ AgentSummary\ Forking' /tmp/cc-debug.log A logging proxy such as LiteLLM https://stackness.dev/tools/litellm also sees every side call; the proxy setup post https://stackness.dev/blog/run-your-own-llm-proxy-to-track-token-usage-litellm-claude-code-codex covers it. The switches that turn each overhead off, and what each one costs Claude Code has no documented switch for agent summary , and DISABLE NON ESSENTIAL MODEL CALLS , which the gist says some packagers set, is in neither the docs nor the changelog. The documented switches below are in the environment variable https://code.claude.com/docs/en/env-vars , settings https://code.claude.com/docs/en/settings-reference and CLI https://code.claude.com/docs/en/cli-reference references as of 1 November 2026; auto-compaction's is spelled DISABLE AUTO COMPACT . | Overhead | Switch | What you lose | |---|---|---| | agent summary | CLAUDE CODE FORK SUBAGENT=0 | Fork mode. Two users measured summaries stopping and two more reported it; one saw no change. Forks and context: fork skills are still summarised | | agent summary | CLAUDE CODE DISABLE BACKGROUND TASKS=1 | All background agents | | agent summary | Flamerix's Bun https://stackness.dev/tools/bun preload via BUN OPTIONS | Panel labels; third-party code, and its v3 gate fails on Windows | | Session title | CLAUDE CODE DISABLE TERMINAL TITLE=1 | Terminal title and status reports | | Recap, suggestions, idle compaction | awaySummaryEnabled , promptSuggestionEnabled , idleCompaction set to false | Each feature; without idle compaction the first message after a break re-reads the context at the miss price | | MCP and skills context | --strict-mcp-config , --disable-slash-commands | MCP servers not passed with --mcp-config ; all skills | | Most startup context | --bare | Hooks, skills, plugins, CLAUDE.md, background agents; needs ANTHROPIC API KEY , so not on a subscription | The labels may matter beyond the panel: Anthropic's reply says summaries are used by "both you and Claude Code", and one reader of the 2.1.314 code reported https://gist.github.com/flamerix-ai/c3905705cc4205e5de3011fa2e74efce they can reach a running agent's context. Nobody has measured a quality change from turning them off. Token optimizer claims against independent checks Of the token optimizer tools in this week's threads, I found an independent check only for Caveman https://stackness.dev/tools/caveman , and none of them touches agent summary . JetBrains ran Caveman on SkillsBench https://blog.jetbrains.com/ai/2026/07/speak-to-ai-agents-like-cavemen-tosave-tokens/ in July: "Advertised saving: 65%. Measured saving: 8.5%", with no significant quality change. claude-token-optimizer https://stackness.dev/tools/claude-token-optimizer claims 90% from its author's one project; its scanner counts Markdown files under docs/ as auto-loaded, which Claude Code does not do, and it counts with a tokenizer whose README says it "is no longer accurate" for Claude 3 and later. The dev.to MCP post https://dev.to/aws-builders/mcp-token-cost-i-cut-my-mcp-server-from-15-tools-to-4-cek cut tool descriptions by 88%, counted in characters, in one run in Kiro https://stackness.dev/tools/kiro . My numbers against Systima and Anthropic My 16,222-token safe-mode figure is half the most-cited startup measurement: Systima measured about 32,800 tokens https://systima.ai/blog/claude-code-vs-opencode-token-overhead on Claude Code 2.1.207 in July 2026, against about 6,900 for OpenCode https://stackness.dev/tools/opencode , most of it tool definitions. Neither run had MCP servers, so the gap is in the two fixed blocks: tool definitions, 14,120 tokens in 2.1.316 against Systima's roughly 24,000, and the system prompt, 2,102 against 6,500. Systima's 72 KB CLAUDE.md added a little over 20,000 tokens, close to the 21,493 the Stackness repository adds. For agent summary , Anthropic's telemetry is the only large sample; everyone else measured their own heavy sessions. On Stackness, as of 1 November 2026, Claude Code is on 8 real public stacks and Bun on 2 how I count https://stackness.dev/about/data-sources , among the AI coding tools developers list https://stackness.dev/categories/ai-tools . Method and sample I ran Claude Code 2.1.316 on macOS on 1 November 2026 on a subscription, with --model sonnet and --no-session-persistence , once per configuration. Context tokens are input tokens plus cache creation input tokens plus cache read input tokens , and costs are Claude Code's own list-price total cost usd . My setup has 20 MCP servers, a dozen plugins and a long global CLAUDE.md, the heavy end; a fresh install sits near the safe-mode row. The summary test ran claude -p --model haiku --debug-file twice and counted AgentSummary Forking lines. The first run warmed caches the second reused, so the 20% compares the summary calls with their own run, not the two runs with each other. Interactive sessions add the title call and arm summaries without the variable; I did not measure them. Key numbers - 0 model tokens for the Claude Code status line script statusline docs https://code.claude.com/docs/en/statusline , read 1 November 2026 . - 16.4% of one organisation's weekly Claude Code spend went to agent summary Flamerix AI, gist of 28 October 2026 . - ~2% of cost and under 4% of requests across Anthropic's telemetry users, ~6% in the terminal Anthropic, 29 October 2026 . - 8% to 26% of spend or tokens in user measurements of subagent-heavy sessions, August to October 2026 . - 30 seconds between summary calls per working background agent, unchanged in 2.1.316 . - 43,394 context tokens in a one-word reply with my full setup, 16,222 in safe mode and 2,102 with no tools my runs, 1 November 2026 . - 8.5% measured output saving from Caveman against 65% advertised JetBrains, July 2026 . New posts by email About one email a week with what we published. No account needed. 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