Cheaplane 🛣️

Keep your premium subscription on the main thread. Offload the grunt work to cheap models — Cheaplane even picks the right one for you. Stop burning premium tokens on boilerplate.

Cheaplane is a tiny single-file MCP server (~250 lines, stdlib + mcp only) that gives your main agent — e.g. Claude Code on a Max subscription — one extra tool: delegate. Your agent keeps doing the thinking (planning, architecture, final review) and hands replaceable grunt work — boilerplate code, formatting, translation, summarizing long docs — to cheap models behind a local LiteLLM proxy (DeepSeek, Kimi, Qwen, …). Think of it as a cheap intern for your premium agent — it churns out the boring parts while you keep thinking.

The trick that makes it safe: the delegated calls and your subscription live in physically separate processes and never share credentials. (why that matters ⬇️)

The trick that makes it effortless: auto-routing. delegate(task) picks the right cheap model from the task itself — code → DeepSeek, long docs → Kimi, Chinese → Qwen. (how ⬇️)

The trick that makes it stick: a per-turn reminder hook so your agent doesn't forget the tool exists — the part most "delegate" tools skip. And a savings ledger shows you what it kept off your quota.

See it in action — your agent hands a chore over; auto-routing sends it to the cheap code model:

delegate("convert to a TypeScript interface: {id, name, email, isAdmin, roles[]}")

interface User {
  id: number;
  name: string;
  email: string;
  isAdmin: boolean;
  roles: string[];
}

↑ a real call's output — not a mockup, and no model picked by hand. That token cost ~90× less than your premium model, and your subscription quota never moved.

The problem

Premium models earn their price on hard problems — but every token counts against your plan, and you burn through quota on churn: reformatting JSON, translating UI strings, summarizing a doc you'll read once. The usual "just use a cheap model" setups force an ugly choice:

• Downgrade the whole agent → you lose main-thread quality on the work that actually matters.

• Route everything through an API key → you stop using the subscription you're already paying for.

Cheaplane keeps the sweet spot: premium main thread for judgment + cheap models for the churn + billing that physically can't cross.

Related MCP server: any-model-plugin

How Cheaplane compares

The popular 2026 move is to swap your whole agent onto a cheap model (DeepClaude-style). Great for raw cost — but it downgrades the thread you actually think with, breaks your other MCP tools, and doesn't even apply if you're on a Pro/Max subscription. Cheaplane takes the opposite bet:

Comparison reflects how backend-swap setups (DeepClaude-style) behaved per public reports in mid-2026; specifics vary by tool and can change.

How cheap is "cheap"?

The grunt work is the easy part — paying premium rates for it is pure waste. Per million tokens (public list prices, mid-2026):

That's an output token costing ~$25 on Opus vs ~$0.28 on DeepSeek — about 90× more for work that doesn't need the smarts. You're on a subscription, so you don't pay that $25 directly — your main thread spends quota, not dollars. That's the whole point: every routine task you offload is premium quota you keep for the hard problems. (Summarizing a 40-page doc on DeepSeek Flash runs ~$0.005 — your quota never even notices.)

Prices are public list rates, mid-2026, and vary by tier/caching — check each provider. The stable takeaway is the order-of-magnitude gap, not an exact dollar saving.

Billing isolation (the whole point)

Most "save money" hacks blur your bills together. Cheaplane keeps them physically apart:

flowchart LR
    A["Main agent<br/>premium subscription"] -->|"delegate(task)"| B["Cheaplane MCP<br/>own process, own key"]
    B -->|HTTP| C["LiteLLM proxy<br/>localhost:4000"]
    C --> D["DeepSeek / Kimi / Qwen<br/>cheap, pay-per-use"]

The Cheaplane process never imports your subscription provider's SDK, never reads its auth, never touches its OAuth token. It knows exactly one thing: an HTTP endpoint (your proxy) and its key. Your main thread bills to your subscription; delegated calls bill to your cheap proxy. The two can't cross — not by policy, by architecture.

Quick start

Fastest path — Claude Code, one script:

git clone https://github.com/millennialdreamer/cheaplane && cd cheaplane
cp litellm.yaml.example litellm.yaml          # then: export DEEPSEEK_API_KEY=sk-...
litellm --config litellm.yaml &               # start the cheap-model proxy on :4000
bash setup.sh                                 # deps + register MCP + reminder hook + verify

setup.sh is idempotent (safe to re-run): it installs deps, registers the delegate MCP server with Claude Code, installs the per-turn reminder hook, and verifies the chain end-to-end. Then start a fresh Claude Code session — done.

Prefer a package? Cheaplane is on PyPI — no clone, no path to hard-code:

pip install cheaplane          # or: uvx cheaplane  /  pipx install cheaplane
claude mcp add delegate cheaplane

You still want the proxy from step 1 below, and the reminder hook is worth it — that part needs the repo.

1. Get an OpenAI-compatible endpoint for the cheap models. Most people run LiteLLM locally as a proxy in front of DeepSeek / Kimi / Qwen. A minimal config is ~5 lines:

# litellm.yaml — exposes DeepSeek under the model_name "deepseek"
model_list:
  - model_name: deepseek
    litellm_params:
      model: deepseek/deepseek-chat        # swap for any provider/model LiteLLM supports
      api_key: os.environ/DEEPSEEK_API_KEY

pip install 'litellm[proxy]'
litellm --config litellm.yaml        # serves http://localhost:4000

That model_name: deepseek lines up with Cheaplane's default alias, so it works out of the box. (deepseek is a built-in LiteLLM provider — no api_base needed; you'd add one only for a custom or self-hosted endpoint.) Already have an OpenAI-compatible endpoint (LiteLLM, OpenRouter, Ollama, vLLM…)? Skip this and just point DELEGATE_BASE_URL at it.

2. Install Cheaplane — from PyPI, or from a clone if you also want the reminder hook and probe.py:

pip install cheaplane        # installs a `cheaplane` command; that's the whole install

git clone https://github.com/millennialdreamer/cheaplane && cd cheaplane
uv sync     # or:  python -m venv .venv && .venv/bin/pip install mcp

3. Register it with your MCP client. Installed from PyPI — the command is already on your PATH:

{
  "mcpServers": {
    "delegate": { "command": "cheaplane" }
  }
}

From a clone — copy .mcp.json.example to .mcp.json in the repo root and fix the path (or use claude mcp add):

{
  "mcpServers": {
    "delegate": {
      "command": "uv",
      "args": ["run", "--directory", "/ABSOLUTE/PATH/TO/cheaplane", "python", "server.py"]
    }
  }
}

4. Verify it end-to-end — with your proxy from step 1 running (handshake → list tools → a real delegated call):

uv run python probe.py
# ✅ chain works (main → MCP → cheap model → back)

Using delegate

Your agent now has delegate(task) — routing is automatic; override only when you want to:

delegate("convert this JSON to a TypeScript interface: …")      #  auto → deepseek (code)
delegate("summarize this 40-page contract: …")                  #  auto → kimi (very long input)
delegate("…Chinese text in the task auto-routes here…")        #  auto → qwen (Chinese copy)
delegate("translate these UI strings to Japanese", "flash")     #  explicit alias still wins

Aliases map to your LiteLLM model_names. Point them at your proxy without editing code — set the DELEGATE_MODEL_MAP env var (a JSON object), or drop a ~/.claude/delegate-model-map.json (hot-reloaded — no restart needed); editing MODEL_ALIASES in server.py also works.

Delegate (let the cheap model do it):

• boilerplate / scaffolding from a clear spec

• mechanical refactors, formatting, lint fixes

• translation; summarizing or extracting facts from long docs

• routine prose: changelogs, docstrings, commit messages

Keep (you do it yourself):

• planning, architecture, technical trade-offs

• final review of delegated output — always you

• talking to the user; judgment calls

• anything where being subtly wrong is expensive

The delegated model sees only your task string — it has no access to your conversation. Make each task self-contained: spec + the actual input + the exact output format you want.

See what you saved

Every delegated call appends one line of metadata only — never the task content — to ~/.cheaplane/usage.jsonl. Ask your agent for savings any time (sample output):

Cheaplane savings — all time
  delegated calls : 184
  tokens offloaded: ~412,300 in / ~365,800 out
  premium cost avoided (Opus list): ~$11.21
  actually spent (DeepSeek-class) : ~$0.16  (≈70× cheaper, in+out blended)
  last 7 days     : 31 calls, ~$2.04 avoided

Numbers are estimates at public list prices — the real win is the premium quota that never left your subscription. The ledger records token counts and model names only; delete the file any time, or set DELEGATE_NO_LOG=1 to turn logging off entirely.

Make your agent actually use it

Here's the dirty secret of every "delegate to a cheap model" tool: installing it isn't the hard part — getting your agent to actually use it is. Drop a tool into an agent and, a few turns into a real task, it forgets the tool exists and grinds through the grunt work itself on premium tokens. The instruction sinks down the context; attention moves on.

Cheaplane ships the fix in the box — three layers you can stack:

1. Skill (SKILL.md) — teaches the agent when to delegate. Works on any client; passive, so treat it as the baseline.

2. A one-line default in your CLAUDE.md / system prompt: "Before doing replaceable grunt work yourself, delegate it." Stronger — but a static instruction still drifts down a long conversation.

3. A per-turn reminder hook — the reliable one (Claude Code). It re-injects the nudge on every prompt, so the habit never sinks out of view. This is what turns an installed tool into a used one.

On other MCP clients (no UserPromptSubmit hook system), use layers 1–2 — wire the one-liner into whatever system prompt your client supports.

Install the hook — safe and idempotent (backs up your settings, merges instead of overwriting, de-dupes on re-run):

bash install-hook.sh            # registers hooks/delegate-reminder.sh as a UserPromptSubmit hook
# verify it's wired up:
python3 -c "import json,os;s=json.load(open(os.path.expanduser('~/.claude/settings.json')));print([h['command'] for e in s.get('hooks',{}).get('UserPromptSubmit',[]) for h in e.get('hooks',[])])"

Start a fresh session, and your agent self-checks every turn: "is this replaceable grunt work? → delegate it."

The reminder costs ~60 tokens per turn — trivially less than the hundreds of premium tokens a single forgotten delegation burns. The hook uses Claude Code's UserPromptSubmit mechanism.

Config

FAQ

Will this leak my subscription credentials? No. The delegate tool runs in its own process and only ever makes a plain HTTP call to the endpoint you configure. It never imports your subscription SDK and never sees its auth — see Billing isolation.

What exactly does the savings ledger record? One JSON line per call: timestamp, alias, model name, and token/character counts. Never the task text, never the model's output. Delete ~/.cheaplane/usage.jsonl any time, or set DELEGATE_NO_LOG=1.

How does auto decide which model to use? A small deterministic heuristic in server.py (_pick_model, ~20 lines you can read and tweak): code signals → deepseek, very long input → kimi, Chinese-heavy → qwen, multi-step language → mimo, short mechanical chores → flash. An explicit alias always overrides it.

How is this different from just using one API key for everything? With a single API key you stop using your subscription entirely and pay per token for all work — including the hard parts. Cheaplane keeps your subscription as the premium main thread and sends only the cheap, replaceable churn elsewhere.

Does it work with anything besides Claude Code? Yes — any MCP-compatible client (Cursor, Cline, Windsurf, …). The main agent just needs to support MCP tools; see Manual setup for the generic JSON config.

Do I have to use DeepSeek / Kimi / Qwen? No. Anything reachable through an OpenAI-compatible endpoint works; the aliases are just convenience labels you can remap with DELEGATE_MODEL_MAP.

Why a proxy instead of calling providers directly? One endpoint, one key, usage logging, and easy model swaps — and it keeps provider keys out of the MCP server entirely.

Roadmap & ideas (help wanted)

Cheaplane's core stays deliberately tiny — but the surface it opens up is big. Shipped so far: ✅ auto-routing (v0.2), ✅ savings ledger (v0.2). Still worth building — proposals and PRs welcome, and most are small enough to be good first issues:

• Smarter routing — the current router is a readable heuristic; better signals (or a learned router) are an open playground.

• Richer savings dashboard — the ledger is plain JSONL; a cheaplane stats HTML view would be lovely.

• Result cache — skip re-delegating identical tasks.

• Auto-review — lint/test code that comes back before you trust it.

• Batch / parallel delegate — hand off several chores in one call.

• More client adoption recipes — the reminder hook targets Claude Code's UserPromptSubmit; Cursor / Cline / others want their own nudge.

Design rule: keep the core single-file and dependency-light — that's the whole point. Build extensions as opt-in, so the 5-minute read stays a 5-minute read.

Contributing

Issues and PRs welcome — it's ~250 lines of single-file Python with no heavy deps, easy to hack on. Add a useful model alias, a routing signal, or a client recipe and send it over.

License

MIT — see LICENSE.