We are using the foundation model endpoints (provisioned and pay-per-token) for the gpt-oss models for a research project. We have been experiencing consistent tool call failures: gpt-oss-20b was failing ~1 out of every 12, while gpt-oss-120b was failing close to 1/4 of the calls.
I noticed that the system prompt length for those models were 10x the length of the other models we were comparing them to (claude-sonnet-4-5, gemma-3-12b, meta-llama-3-1-8b-instruct), so I made gpt-oss-20b leak its system prompt (on the first try) and it contains the phrase "You have no access to tools..." (see attached screenshot).
Why is that included in the system prompt? I haven't seen that in other cloud provider endpoints. We would like to reliably use those models for agentic loops, but obviously we can't do that when they fail to call tools 1/4 of the time.
