Some ChatGPT App Store users lose access to exposed MCP tools after one tool call

I wonder if this is related to the new version of GPT-5.5 Instant released last week. Can anyone from OpenAI confirm whether Apps on Instant have a smaller effective context or tool-descriptor budget? I saw docs implying context size for Instant is now 16K tokens (and it used to be 27K tokens).

Specifically, can large MCP tools/list payloads - descriptions, input/output schemas, annotations, metadata, etc. - cause exposed tools to become unavailable or stop being selected after an initial tool call?