Meet TokenEconomizer: Microsoft’s Plugin That Cuts Coding Agent Costs by Up to 30.9%

A team of researchers from Microsoft Research and UC Berkeley have released TokenEconomizer, an open-source cost controller for coding agents.

TokenEconomizer is a plugin that learns from past sessions in a repository to cut waste in later ones.

It works with Claude Code, Codex, GitHub Copilot CLI and Pi.

It does not touch model weights or agent code.

On 277 SWE-Bench tasks, it lowered mean cost by 18.4% to 30.9% across 5 agent-model settings.

TL;DR Package: A standard-library Python package and agent plugins, with 3 switchable mechanisms.

Runs on: Any machine running Claude Code, Codex, Copilot CLI or Pi with Python 3.10+.

No GPU and no API key of its own.

Performance: 18.4% to 30.9% lower mean SWE-Bench cost, and cheaper in all 30 repository-setting cells.

Best: 30.9% lower cost on Claude Code with Opus 4.8 (33.2% when combined with RTK).

Worst: Only 6.4% to 9.3% savings on ReposVul audits; Pass@1 drops 1.0 point on Opus 4.8.

Why do coding agents waste tokens?

Every agent turn re-bills the system prompt, every loaded tool schema and the full history.

The research team profiled 60 SWE-Bench tasks across 6 repositories using Claude Code with Opus 4.8.

They found 3 recurring sources of waste: Repeated discovery: once 5 tasks precede the current one, 30% of tool calls repeat an earlier action.

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