ToolChoiceConfusion: Causal Minimal Tool Filtering for Reliable LLM Agents
Why This Matters
Directly addresses LLM integration, agent architectures, and fine-tuning, with specific technical content on Causal Minimal Tool Filtering (CMTF) and empirical results.
Abstract
Large language model agents increasingly rely on external tools, but larger tool menus can reduce reliability and efficiency by increasing wrong-tool calls, premature actions, and token cost. Existing tool-selection methods often optimize semantic relevance, exposing tools whose names or descriptions match the user request. We argue that relevance is insufficient: a tool may be related to the task while still being unnecessary or premature at the current step. We propose Causal Minimal Tool Filtering (CMTF), a training-free method that selects tools by causal sufficiency. CMTF uses lightweight precondition-effect contracts to expose only the minimal next-step tool frontier needed to advance from the current state toward the user goal. Across multi-step tool-use tasks, we compare CMTF with all-tools exposure, keyword retrieval, state-aware filtering, and causal-path ablations, measuring task success, wrong-tool calls, premature actions, tool exposure, and token cost. In the main benchmark with 102 tasks, 100 tools, four LLM backends, and 2448 task-method-model runs, CMTF matches the strongest causal baseline in aggregate success while reducing visible tools from 100 to one per step and reducing token usage by about 90% relative to all-tools exposure.
Links
Metadata
Save to Vault
Save this article directly to your Obsidian vault. Opens Obsidian with the note pre-filled.
Will save to: vault/inbox/signals/2026-06-07-toolchoiceconfusion-causal-minimal-tool-filtering-for-reliable-llm-agents.md