browser.set_viewport

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

With no annotations, description should disclose behavioral traits like side effects (e.g., triggers resize events, affects element visibility) but only states the resize action itself.

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?

Single sentence, no unnecessary words. However, it is slightly terse and could be expanded with critical details without losing conciseness.

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?

No output schema, no annotations, and only a vague description. Missing information on return values (success/failure), side effects, and necessary preconditions like an active session.

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 0%, so description must compensate. It does not explain the session_id parameter or constraints (e.g., width/height range), adding no meaning beyond the schema's titles and min/max.

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 (Resize) and resource (browser viewport), and clearly distinguishes from sibling tools like screenshot or observe which have different purposes.

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?

No guidance on when to use this tool vs alternatives, no prerequisites mentioned (e.g., session must be open), and no conditions where resizing is not appropriate.

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