Cost Tracking

yoyo estimates the cost of each interaction so you can monitor spending.

Per-turn costs

After each response, you'll see a compact token summary:

  ↳ 3.2s · 1523→842 tokens · $0.0234

With --verbose (or -v), you get the full breakdown:

  tokens: 1523 in / 842 out  [cache: 1000 read, 500 write]  (session: 4200 in / 2100 out)  cost: $0.0234  total: $0.0567  ⏱ 3.2s

• cost — estimated cost for this turn
• total — estimated cumulative cost for the session

Quick cost check

Use /cost for a quick overview with a breakdown by cost category:

  Session cost: $0.0567
    4.2k in / 2.1k out
    cache: 1.0k read / 500 write

    Breakdown:
      input:       $0.0126
      output:      $0.0315
      cache write: $0.0031
      cache read:  $0.0005

Detailed breakdown

Use /tokens to see a full breakdown including cache usage:

  Session totals:
    input:       120.5k tokens
    output:      45.2k tokens
    cache read:  30.0k tokens
    cache write: 15.0k tokens
    est. cost:   $0.892

Supported models

Costs are estimated based on published pricing for all major providers:

Anthropic

Fleet models (Fable 5, Fable 5.1, Opus 5, Opus 5.5, Opus 4.8, Sonnet 5, Haiku 4.5) read their pricing directly from yoagent's model presets at runtime, so their rows below are informational — the preset is the source of truth. Until Day 222 (#1003) Opus 5.5 and Fable 5.1 were matched by their older sibling's preset and priced as Opus 5 ($5 / $25) and Fable 5 ($1 cache read); each now gets its own. Sonnet 5.5 has no yoagent preset either; until Day 224 it was priced as Sonnet 5 ($0.20 cache read). yoyo now carries its own arm (Sonnet 5's window and limits, $0.10 cache read, from the models.dev catalogue).

Haiku 5.5 is not yet a yoagent preset, so yoyo carries its own (1M context, 128K max output, prices from Anthropic's pricing page). Anthropic charges it more above 100,000 prompt tokens ($0.50 in, $0.625 cache write, $0.05 cache read, $2.50 out). Since Day 222 the per-turn breakdown in /cost prices each turn whose own prompt (input + cache tokens) is over 100,000 at those tier rates, marks it with *, and adds a footnote; a prompt of exactly 100,000 stays at the base rate. The tier is per request, so it is applied only where yoyo has one request's usage. The session cost line, /tokens, the per-response ↳ line and the --verbose totals do not apply the tier and still use the base rates, so they understate a Haiku 5.5 session with very long prompts. When the two disagree, the per-turn total is the closer one (it covers only turns still in the conversation, so after /compact it can be lower). A [model_pricing] override for the model replaces its pricing wholesale and no tier applies. Haiku 5.5 is the only model yoyo currently prices with a tier.

OpenAI

Google

Gemini 3.6 Flash is billed at Google's regular rate; Google charges an introductory $0.75 / $3.75 through 2026-12-31, so until then /cost reads about twice the bill. The 3.1 image, TTS and live ids and gemini-3.5-live-translate-preview have exact prices too (image or audio output rates). Other gemini-3* flash ids Google's pricing page does not list (for example gemini-3.5-flash) are still estimated at $0.15 / $0.60, and other gemini-3* pro ids (for example gemini-3-pro-preview, gemini-3-pro-image-preview) at $1.25 / $10. Gemini 3.1 Pro is billed at its base rate; Google charges $4 / $18 for prompts over 200K tokens, which /cost does not model. Gemini 3 Pro Image is billed at its image output rate ($120); its text output is $12.

DeepSeek

Two things to read these numbers with. First, they are off-peak prices: DeepSeek doubles them on weekdays 01:00–04:00 and 06:00–10:00 UTC, so a cost yoyo reports for a DeepSeek session is a lower bound — during a peak window the true cost is up to 2x what is shown. Second, this table is a set of hardcoded literals: when a provider changes its prices, nothing changes here automatically. A drift alarm exists but is opt-in, because it fetches models.dev over the network: cargo test --bin yoyo audit_table_against_models_dev -- --ignored lists every row that disagrees. Open drift is tracked in #1012. deepseek-v4-flash (the id the evolve loop runs on) is a legacy name DeepSeek still serves as V4.1-Flash, so it is priced as deepseek-flash; deepseek-r1, deepseek-v3 and deepseek-v4-pro are carried unchanged and, at the time of writing, have not been checked against a second source.

Mistral

xAI (Grok)

Groq (hosted models)

MTok = million tokens.

OpenRouter

Models accessed through OpenRouter (e.g., anthropic/claude-sonnet-4-20250514) are automatically recognized — the provider prefix is stripped before matching.

Custom pricing

The built-in table is list price. If your real rate differs — a negotiated contract, a volume discount, a proxy or gateway that re-prices, a self-hosted model whose marginal cost is electricity, or any OpenAI-compatible endpoint yoyo has no entry for — you can say so in your config file:

[model_pricing."my-model-id"]
input = 1.50    # USD per million input tokens
output = 7.00   # USD per million output tokens

Precedence: your override > the built-in preset > the built-in table. Your number always wins for the model id you name.

Rules:

• Model ids match exactly. Pricing gpt-4o does not re-price gpt-4o-mini, and does not re-price openai/gpt-4o. Write the id exactly as yoyo reports it in /model.
• Both rates are required. An entry missing input or output, or carrying a non-number or a negative number, is ignored entirely and named on startup — yoyo will not apply half a price, because the resulting number would belong to no source at all.
• Zero is a valid price. A self-hosted model whose marginal cost per million tokens really is zero reports $0.0000 rather than reporting nothing.
• Overrides cover input and output only. A model you price yourself is costed with cache-write and cache-read rates of zero; cache-token rates are not configurable today.

This makes the number correctable, not correct: an override is a claim you made, and yoyo has no way to verify it against your actual invoice.

[model_pricing] is a table, not a scalar, so it is not settable through /config set — edit your config file directly (/config edit).

Spending warning

Set a budget in US dollars and yoyo prints one stderr warning when this session's estimated spend crosses it. It is a warning only; nothing is stopped. Sources, highest priority first: --cost-warn <usd>, the YOYO_COST_WARN_USD environment variable, and cost_warn_usd in .yoyo.toml. It is off when none is set.

The value must be a positive number. An invalid one (abc, -1, 0, nan) prints a warning at startup naming where it came from, before any tokens are spent. If no other source gives a usable value, the cost warning is off for that run. An empty YOYO_COST_WARN_USD counts as unset.

Limitations

• Cost estimates are approximate — actual billing may differ slightly
• For unrecognized models, no cost estimate is shown
• Cache read/write costs only apply to Anthropic models; other providers show zero cache costs
• Pricing may change — check your provider's pricing page for the latest rates, or pin your own rate with [model_pricing] above

Keeping costs down

• Use smaller models (Haiku, Sonnet, GPT-4.1 Mini, Gemini Flash) for simple tasks
• Use /compact to reduce context size (fewer input tokens per turn)
• Use single-prompt mode (-p) for quick questions to avoid accumulating context
• Turn off extended thinking for routine tasks