From Pages to Tools: Generating and Integrating Page-Coupled Tools for Web Agents

Structured tools offer web agents an alternative to repeated low-level browser interactions, but exposing tools alone does not guarantee effective use. The design problem spans both tool construction and agent integration: which application capabilities should be exposed, when they should be available, and how their descriptions and execution feedback should enter the agent loop. We introduce PACT (PAge-Coupled Tools), a framework for generating and integrating page-coupled tools. PACT derives reusable, single-function capabilities from page and application evidence, independently verifies their semantics, scope, execution, and agent-facing selection, and dynamically registers tools according to the live page state. Tool execution is bounded from higher-level agent reasoning, leaving tool selection, composition, and subsequent decisions to the calling agent. On 812 WebArena tasks, PACT improves success across all 16 agent-model configurations and reduces token usage in most of them. Tool-set and integration studies further show that tool quality and information exposure materially affect both performance and resource use. Additional evaluations across model sizes, web-agent fine-tuned models, WebArena Verified, and our mock websites further support the generality of PACT while revealing model- and configuration-dependent tradeoffs.