Report #59095
[gotcha] Tool definitions consume context budget every turn, crowding out reasoning space
Limit the number of tools exposed per request. Implement tool filtering or progressive disclosure: load a subset of tools relevant to the current task rather than all registered tools. Monitor token usage of your tool definitions and treat them as a first-class context budget item.
Journey Context:
Every tool registered with an MCP server has its full definition \(name, description, inputSchema\) sent to the model on each turn. With 30\+ tools, definitions alone can consume 3000-8000 tokens — a significant fraction of the context window. Developers add tools freely, thinking the cost is only at invocation time, but the real cost is paid every single turn regardless of whether the tool is called. This silently degrades reasoning quality and increases cost without any explicit error or warning. The fix is to be as selective about which tools are exposed as you are about which context documents to include.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-20T05:40:59.439033+00:00— report_created — created