JoaoEquer Token efficiency
Tokens are the working memory of the session. Every verbose command output gets re-read on every subsequent turn, so waste compounds: a 2,000-token git diff costs ~20,000 tokens over the next 10 turns. Two fronts: tooling (RTK) and habits.
RTK (Rust Token Killer)
rtk-ai/rtk is an open-source CLI proxy (single Rust binary, Apache 2.0) that compresses command output before it reaches the context window — 60–90% savings on test runners, git operations and package managers. It runs locally and hooks into the agent's official extension points (Claude Code PreToolUse hook); it does not touch API traffic.
Setup (once per machine)
# Install (official script; on Windows, native binary works since v0.37.2)
curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh
# Activate for your harness — hook-only avoids extra per-turn context
rtk init -g --hook-only # Claude Code
rtk init -g --gemini # Gemini CLI
rtk init -g --agent cursor # Cursor
Restart the agent afterwards. The hook rewrites Bash calls transparently (git status → rtk git status); the agent doesn't need to know RTK exists. Prefer --hook-only: the alternative injects an RTK.md into context on every turn, which spends tokens to save tokens.
What it actually covers (calibrate expectations)
- Big wins: test runners showing failures only (
pytest,vitest,cargo test— 90%+),git diff/log/status, package manager install noise,tsc/lint output grouped by file. - Not covered: the agent's native Read/Grep/Glob tools bypass the Bash hook. In read/edit-heavy sessions RTK has little to intercept — that's expected, not broken.
- Verify it's working:
rtk gainshows accumulated savings;rtk discoverfinds commands you ran that could have been compressed. - Failure safety: when a command fails, RTK saves the full unfiltered output to disk so nothing important is lost.
Habits that save more than any tool
- Ask for scoped output:
git log -n 5beatsgit log; run the failing test file, not the whole suite. - Don't paste what the agent can read: reference file paths instead of pasting file contents into the prompt.
- One domain per session: long mixed sessions accumulate stale context; a fresh session with a good CLAUDE.md/AGENTS.md beats a bloated one.
- Keep context files lean: the project's AGENTS.md is re-read constantly — it pays rent on every turn. If a section isn't changing behavior, cut it.
Session management
/clearbetween unrelated tasks. A session accumulates every file read and every dead end along the way;/clearstarts the next task without dragging that weight. Prefer it over continuing one thread across unrelated work./compactfor a long session you still need. Summarizes history to free up context without losing the thread — use when one task genuinely has to keep going past the point where tool output dominates the window./rewindto back out of a wrong turn. Rolls the conversation and/or code back to a checkpoint — cheaper than manually undoing several turns of accumulated edits./rename <name>+claude --resume <name>to give a long-running task a memorable session instead of hunting through theclaude --resumepicker./contextshows what is actually filling the window — check it before assuming a slowdown is the model's fault rather than a bloated AGENTS.md or an unnecessarily wide file read.- Session transcripts live in
~/.claude/projects/<path>/and are pruned after 30 days by default (cleanupPeriodDaysinsettings.json). Don't treat them as permanent history — the delivery log indocs/log/is the permanent record (git-workflow).
Model tiering by leverage
- Strong model plans, mid-tier model executes. Spend the highest-capability model on exploring the codebase and producing the plan; a faster/cheaper model carries out an already-approved, well-specified plan just as well, for a fraction of the tokens.
- Never the inverse. A weak model producing the plan compounds mistakes silently through every step that follows; a weak model executing a plan a strong model already approved just executes — review the diff either way.