Are you using an API, or running locally? If so, are you running with a quant, or other 'optimisations'?

I've been using it via openrouter pretty heavily as my daily driver for the past week and loving it, have never experienced incoherent rubbish even at 500k+ contexts (that's usually way higher than I'd typically compact at), and tool calling reliability is better than Opus 5 in the Claude Code harness.

Modern Anthropic models frequently get tool calls wrong, invent non-existent references or SQL tables, or have gibberish CJK characters in the output, like out of nowhere. Of course, they're great at self-recovery after an incorrect tool call, but so is Deepseek v4 flash.

If you're running a quant, and esp with a quant'd KV cache, then yeah, not surprised if you're getting incoherent results; but you're not running the real/full model.

Also, which harness? Try something like Pi or OMP. Models perform better in these harnesses than Claude Code: https://www.databricks.com/blog/benchmarking-coding-agents-d...

The main reason to use Cladue Code is a subsidised Anthropic subscription. If you're on API rates, you should not use Claude Code; you pay more for worse results. Claude Code is sadly quite bloated these days, and comes with a lot of proprietary context window garage like claude design skills, claude.ai artifacts, etc that you probably don't use, and if you do, well, you can add it.