get_viewport

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

The readOnlyHint annotation already indicates a safe read operation. The description adds valuable behavioral context by specifying the return structure (center, zoom, bounds) and the meaning of zoom (1.0 = 100%). No contradiction exists, and the added detail goes beyond the annotation.

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, well-structured sentence. It front-loads the main action and return type, then provides clarifying details. No unnecessary words or repeated information from the schema or annotations.

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?

For a simple tool with no parameters and no output schema, the description covers the essential behavior: what is returned and what each field signifies. The only minor gap is not specifying the coordinate system or reference frame for 'bounds', but this is a reasonable omission for a viewport getter.

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 input schema has zero parameters, so there is nothing to document. The baseline for no-parameter tools is 4, and the description compensates by explaining the output semantics in detail, which is especially useful given that no output schema exists.

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 tool's purpose with a specific verb ('Return') and resource ('current page viewport'), and enumerates the exact return fields. This makes it easy to distinguish from sibling getters like get_selection or get_document, which target different aspects of the document state.

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 state when to use this tool versus alternatives, nor does it mention any exclusions. However, the purpose is self-evident as a read-only viewport query, so usage is implied. Absence of explicit sibling differentiation keeps this at a mid-range score.

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