viewport

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety/idempotency profile is covered. The description adds nothing beyond that: it does not say what gets destroyed (current aspect ratio, camera framing, selection state) or whether the change persists across renders or sessions. With annotations present the bar is lower, but the description contributes essentially no behavioral context.

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?

One short, front-loaded sentence with no wasted words, which is structurally fine. However, it is under-specified rather than genuinely concise, leaving nothing for the agent to rely on beyond the title-like phrase.

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 tool is simple (two required params, output schema present, annotations present), so the description needn't explain return values. Even so, for a mutation of view state in a 120+ tool PyMOL server, it should at minimum say whether the change is transient and how it relates to sibling camera tools; neither is present.

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% and both parameters carry their own descriptions ("Viewport width in pixels", "Viewport height in pixels"), so the baseline of 3 applies. The description does not clarify the notable oddity that width/height are typed as strings, nor any constraints such as minimum values or aspect-ratio handling.

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 names a specific verb plus resource ("Sets the viewport size"), so an agent knows it mutates the camera/viewport dimensions rather than content. It does not distinguish itself from adjacent camera tools like zoom, full_screen, or orient, which also affect the viewport.

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?

There is no guidance on when to call this instead of the many sibling camera tools (zoom, zoom, zoom, full_screen, zoom-to-fit behaviors). No prerequisites, no exclusions, no note about whether this replaces or composes with existing camera state.

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