LeanToken

Code intelligence for agents: find the code that matters and keep your context window and tokens lean.

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• MCP Registry name: mcp-name: io.github.morluto/leantoken

Install · Why LeanToken · Tools · CLI · How it works · Docs

Measured token savings: In a controlled 60-run study, LeanToken used 20.1% fewer model input tokens than the agent's built-in tools with limited repository exploration, and 37.6% fewer than those tools with broad exploration. See exactly how it was measured in the measurement methodology.

Quick start

Add LeanToken to Claude Code, Cursor, OpenCode, Codex, Gemini CLI, or Antigravity:

npx leantoken setup

Restart or reload the configured clients, then verify the connection and first retrieval from a repository:

npx leantoken doctor

Try a broad task such as: Find the code related to request cancellation before editing. LeanToken helps the agent start with leantoken.context, while its normal tools remain available for edits, builds, and tests.

Inspect LeanToken's observed repository-local token accounting:

npx leantoken savings

npx leantoken setup --claude --codex --yes
npx leantoken setup --all --yes

npx leantoken setup --codex --cursor --dry-run

npx leantoken remove

npx leantoken runtime list
npx leantoken runtime prune --dry-run
npx leantoken runtime prune --yes

npx --yes leantoken@latest setup --refresh --yes
npx --yes leantoken@0.1.8 setup --refresh --yes --allow-outdated

Common agent workflows

LeanToken works best as a small evidence loop rather than a one-shot repository dump:

1. Orient autonomous triage in one call. Start an uncertain broad task with context and plan_only: false, then use the materialized evidence directly. Make at most one focused follow-up only when coverage identifies a concrete missing implementation or regression-test owner.
2. Continue without resending source. Pass the prior receipt_id on the next context call, or pass returned fragment hashes as known_hashes. The response reports exact and overlapping omissions instead of silently charging the same evidence again.
3. Investigate an observed failure. Use the investigation workflow and provide only directly observed failure_traces, paths, symbols, or test intent in workflow_evidence. Follow with exact search, outline, or read calls for the owners the evidence identifies.
4. Review a change. Use the review workflow with base_revision set to BASE..HEAD and strict_changed_paths: true. Request a handoff when another agent needs a compact manifest of selected hashes, changed paths, assumptions, and completed validations without copied source bodies.

This one-call contract is for autonomous repository triage, not a limit on implementation agents. Human review and control-plane flows can still preview expensive or high-risk retrieval with plan_only: true before materializing. The repeated multi-agent context suite found that an iterative LeanToken profile used 50.9% more total input than thin native, while the frozen one-context-plus-optional-one-search profile saved 20.1% and had 15/20 path-set successes. Those results cover four pinned triage tasks; they do not prove a universal implementation workflow.

Explicit focus constraints are contracts. When a request supplies focus_paths, exact focus_symbols, and minimum_fragments_per_focus_path, LeanToken generates candidates within the documented per-file bounds and reports a coverage failure when distinct ranges cannot satisfy the minimum. Explain-profile plans and materialized responses also identify the bounded allocation boundary that generated, reserved, selected, or suppressed each focus candidate without changing ranking.

Why LeanToken

Most agents start by searching widely and reading whole files. LeanToken narrows that work in stages:

Your coding agent still handles editing, commands, tests, and conversation. LeanToken finds and returns the code those tasks need.

LeanToken does not create one giant prompt file. It answers focused searches and reads as the agent needs them.

Example

For a task like fix request cancellation during shutdown, an illustrative bounded result might look like this:

Budget: 1,200 source tokens

Selected evidence:
  src/services/executor.rs        lines 137-147, 251-259
  src/services/reconciliation.rs lines 148-175, 257-272

The agent receives these ranges instead of both full files. If the budget is too small, the response also says what was left out. Paths, scores, receipts, JSON, and MCP transport wrappers are not part of this source-token budget; see token accounting for the measured boundaries.

Available tools