viewport

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

With no annotations, the description carries the behavioral burden. It discloses that the active web viewport is modified and that the operation times out after 90 seconds. However, it does not state whether the resize persists across subsequent commands, is reversible, or impacts other workflows beyond snapshots/screenshots.

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 only two sentences, front-loads the core action and purpose, and includes a useful timeout detail. Every sentence earns its place with no filler.

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?

The description covers the tool's purpose, timing, and timeout behavior. The input schema documents all 18 parameters and an output schema exists, so return-value and parameter details are already structured. Minor gaps around persistence and side effects are already reflected in behavioral transparency.

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 description coverage is 100% and already documents width and height in CSS pixels. The description adds no additional parameter-specific meaning, so the baseline of 3 applies.

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 ('active web viewport') and explains why it matters before snapshots/screenshots. This clearly distinguishes it from sibling tools like screenshot and snapshot.

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 gives clear contextual guidance: use it before taking snapshots or screenshots, especially for fixed-layout or 100vh apps. It does not explicitly mention alternatives or when not to use it, but the use-case framing is strong enough for an agent to select it appropriately.

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