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Use RTK to Reduce Token Usage

rtk-ai/rtk is a Rust CLI proxy that compresses common command outputs before they are sent to your coding agent context.

In practical OpenCode sessions, this can reduce prompt/context token usage significantly on repetitive commands like git status, git diff, ls, grep, test runners, and build logs.

What RTK does in OpenCode​

RTK can integrate with OpenCode through an OpenCode plugin hook and rewrite Bash commands to rtk ... equivalents automatically.

Examples:

  • git status → rtk git status
  • git diff → rtk git diff
  • ls → rtk ls
  • rg pattern . → rtk grep pattern .

That means you keep the same command habits while sending denser, less noisy output to the model.

Install RTK​

Choose one method.

brew install rtk

Script install (Linux/macOS)​

curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh

Verify installation​

rtk --version
rtk gain
Name collision on Cargo

Another crates.io package is also named rtk. If you use Cargo and install the wrong one, RTK commands such as rtk gain will fail.

Use the upstream Git install command from the RTK docs when installing via Cargo.

Set up RTK in OpenCode​

Install the global OpenCode plugin:

rtk init -g --opencode

This creates:

  • ~/.config/opencode/plugins/rtk.ts

Then restart OpenCode.

Validate that OpenCode hook is active​

After restart, run a few normal commands in OpenCode:

git status
git diff
ls

If RTK is hooked correctly, these commands are rewritten internally and produce compact summaries.

Use these checks as well:

rtk init --show
rtk gain --history

Important limitation​

The OpenCode plugin hook applies to Bash tool execution only. Built-in non-Bash tools (for example native file readers/searchers) are not rewritten by this hook.

If you want RTK compaction for those workflows, use shell commands or explicit RTK commands such as:

  • rtk read <file>
  • rtk grep <pattern> <path>
  • rtk find "*.ts" .

Optional tuning​

RTK supports config tuning in ~/.config/rtk/config.toml (or macOS app support path), including:

  • rewrite exclusions (hooks.exclude_commands)
  • tee/full-output capture behavior for failures
  • tracking database location

This is useful if you want RTK in most places but need raw output for specific commands.

When to use RTK in this docs stack​

RTK is most useful when you frequently run command-heavy coding sessions and want to reduce token burn without changing your normal terminal habits.

If your sessions are mostly short or rely heavily on OpenCode built-in non-Bash tools, the impact will be smaller.

References​