browser_hit_test_rel

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses the implementation ('elementFromPoint'), the return fields (tag, id, class, rect, pointerEvents, cursor; iframe src/name), and implies a read-only, non-mutating operation. It lacks an explicit statement about no side effects, but the overall behavior is well conveyed.

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 three concise sentences: what it does, what it returns, and its purpose. Each sentence earns its place with no fluff or redundancy. It is front-loaded with the core action and remains highly readable.

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?

There is no output schema, so the description must explain return values, which it does by listing the fields. With no annotations, it also covers the behavioral aspect. It does not mention error cases (e.g., element not found) or clarify that it does not perform a click, but for a simple hit-test tool, the provided information is largely sufficient.

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%, so the baseline is 3. The description adds minimal extra parameter meaning beyond the schema—it mentions that rx/ry are relative in [0..1] and that the operation is inside a frame, but these are already captured in the schema descriptions. The description does not provide additional context about the parameters (e.g., coordinate mapping, frame chaining nuances).

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 verb ('Return'), the resource ('element at relative (rx, ry)... inside the frame'), and the method ('via elementFromPoint'). It also explains the purpose ('Confirms where clicks land'), distinguishing it from sibling tools like browser_click_at_rel (which clicks) and browser_frame_bbox (which returns geometry).

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 by stating the tool confirms where clicks land, implying use for hit-testing/verification before actual clicks. It does not explicitly name alternatives or exclusions, but the intended use case is evident from the description and the sibling tool names.

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