get_element_rect

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

The annotations already declare readOnlyHint=true, so the agent knows this is a safe read operation. The description adds that the position is relative to the app window, which is useful context beyond the schema. However, it does not disclose what happens if the element is not visible or not attached to the DOM, and there is no output schema to clarify the exact return format.

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, clear sentence that directly conveys the tool's purpose. It is front-loaded with the action and resource, and contains no extraneous words. It could be slightly improved by front-loading what it gets (position/size) before the parenthetical detail.

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?

Given the tool has one parameter, annotations, and no output schema, the description provides a basic level of completeness. However, it does not mention the return type or structure, which is important for an agent to use the output. The description also lacks context about coordinate system or potential errors (e.g., stale element).

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?

With 100% schema description coverage, the baseline is 3. The description does not add any extra meaning beyond the schema for the single parameter elementId. It does not elaborate on what constitutes a valid elementId (e.g., a recently returned ID, or its type structure).

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 ('Get the position and size') and the resource ('an element'), with specifics about the coordinate reference ('relative to the app window'). This distinguishes it from get_window_rect (which gets the browser window's position/size), but does not explicitly differentiate from other getter tools like get_element_info or get_element_screenshot.

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?

There is no guidance on when to use this tool versus alternatives like get_element_info (which may return similar bounding box data) or get_window_rect. The description does not mention prerequisites (e.g., that find_element must be called first), nor does it clarify when calling this tool is appropriate versus other element query tools.

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