TL;DR: Claude Code token costs grow fast on agent-heavy workflows because every tool definition gets injected into the context. An AI gateway in front of Claude Code lets you cache responses, swap to cheaper models, and use Code Mode to cut tool definition overhead. After testing the setup with Bifrost , the largest single optimisation is Code Mode for MCP, which reduces tool definition tokens by 58% to 92.8% depending on tool count. This post assumes familiarity with Claude Code , MCP server basics, and what ANTHROPIC_BASE_URL does in CLI agents. Where Claude Code Token Cost Comes From Three places drive cost on a typical Claude Code workload. First, the model itself. Default Claude Code uses Sonnet for most tasks and Opus for harder ones. Opus is several times more expensive per token than Sonnet, and Sonnet is several times more than Haiku. Second, repeat work. Claude Code re-reads files, re-runs grep, and re-thinks the same problem inside long sessions.…