session_click

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only provide a title, so the description carries the full burden. It thoroughly discloses behavior: scrolls into view, fires DOM click, re-verifies element, returns clicked:false with reasons on failure, never silent no-op, may navigate, and session state persists. This is exceptionally transparent and goes beyond basic expectations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single dense paragraph but well-structured: it opens with the core action and source, then details pre-conditions, failure modes, side effects, and persistence. It is not overly verbose for the amount of critical information it conveys, though breaking it into bullets could improve readability. It earns its length by covering essential behavioral details.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite lacking an output schema, the description explains return values (clicked:false, reason, covered_by, url, text_after), failure modes, navigation side effects, and session persistence. For a two-parameter tool, this is remarkably complete—an agent has everything needed to invoke it correctly and interpret outcomes.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with both parameters described (index from /state output, session_id). The description adds value by clarifying that index must come from the most recent session_state and re-list after navigation, plus explaining how the index is used (re-verification). This enriches the schema meaning beyond the basic descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('Click an interactive element'), the resource (element by index in a live browser session), and the source of the index (session_state output). It also distinguishes itself from sibling session_click_xy by specifying index-based clicking, making it easy to select the right tool.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear context: indexes come from the most recent session_state, and it advises re-listing after navigation. It implicitly differentiates from session_click_xy (coordinate-based) by emphasizing index-based selection, though it doesn't explicitly name the alternative. It covers when the tool may not work (page changed) and how to handle it, giving sufficient usage guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.