get_viewport_size

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

With no annotations provided, the description carries the full burden of explaining behavior. It correctly implies a read-only operation ('get') with no side effects and highlights that the value is 'current,' but it does not describe the return shape, units, or possible variations. This is a moderate gap, though the simple getter nature reduces the risk.

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 five words long, contains no filler or redundant phrasing, and places the core action and resource right at the front. Every word earns its place for the information being conveyed.

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 low complexity and zero parameters, the description is mostly sufficient for selecting and invoking the tool. However, there is no output schema and the description does not specify the exact return format (e.g., an object with width/height, a string, or pixel units), which leaves some ambiguity about how to interpret the result.

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?

The tool has zero parameters and 100% schema coverage, so the baseline is 4. The description's 'current' reinforces that no input is needed because the tool reads live state, adding a small amount of meaning beyond the empty schema.

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 states a specific verb ('Get') and a specific resource ('current viewport dimensions'), making the tool's function immediately clear. It also distinguishes itself from the sibling set_viewport_size through the get/set pairing, so an agent can tell them apart without inspecting schemas.

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 does not explicitly say when to use this tool versus alternatives, but the purpose is straightforward enough that an agent can infer 'use this when you need the current viewport dimensions.' There is no stated exclusion or comparison with other inspection tools like evaluate or browser_snapshot, so the guidance is only implied.

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