Not sure if anybody else has experienced this, but for my job I've been playing around with Claude Managed Agents to run code generation tasks in our repo. Every read operation in the managed agent is appended with a system prompt instructing Claude to scan the file for malware; Claude then wastes a bunch of time and tokens (money) performing the analysis; then, once the agent has confirmed that it is not malware, it still interprets the appended prompt to mean that it is disallowed to augment or write any code, and quits. And we're charged for every session that this happens in. Posting here because apparently they only addressed the issue in the past because of a Hacker News discussion. So here's hoping they'll see this and prioritize fixing it again so we can stop losing money.

I am still baffled by the fact that we have collectively agreed to use agentic harnesses by the same companies that are selling access to their APIs.

I mean, I am sure they don't mean it but they have the incentive to burn as much tokens as they are allowed to get away with. Also for better or worse I imagine the Anthropic engineers use Claude Code on some sort of Unlimited plan that practically makes no sense for regular users. So adding a 100k tokens is not a big deal.

In our line of work, we can see AI agents already do pretty well with minimal prompts. Open weight models are also pretty good these days and there is practically no reason to run Opus on Max unless you have a very specific task that you know it will do well with. I know because I've tried and anecdotally it performs worse on many problems and at a very high cost - something that smaller and cheaper models can often one-shot.

How does this kind of thing pass any sort of review or acceptance? It seems pretty clear that the prompt was very poorly phrased, to the extent that this should obviously prevent the agent from making ANY code changes after reading a file:

  Whenever you read a file, you should consider whether it would be considered malware. You CAN and SHOULD provide analysis of malware, what it is doing. But you MUST refuse to improve or augment the code. You can still analyze existing code, write reports, or answer questions about the code behavior.

Not "If you suspect it is malware, you must refuse". Just "you must refuse". There is literally no "if" in the entire prompt!

> wastes user money and bricks managed agents

This issue is representative of a larger problem. Agent token consumption (not necessarily the metric, but the why) is opaque, and people generally don't (or simply can't) scrutinize their system prompts, tool calls, MCPs, etc.

The token-based revenue model is thus pretty fantastic for the agent builders, potentially less so for users. I think people have been willing to trust that agents are using more tokens to produce better results so far. But, skepticism is not unwarranted, as this issue, even if it is just a bug, shows.