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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context: it returns only the active version, the history payload can be large, and the returned screenId is the value design consumes. It stops short of discussing auth or guarantees around large payloads.

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?

Four compact sentences, front-loaded with the core purpose and followed by scope, alternatives, and routing. Slight redundancy with the schema on the allVersions payload warning keeps it from being perfectly lean.

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?

With an output schema present and rich annotations, the description need not explain return values, and it covers the key routing decisions an agent needs. What remains is minor (no mention of other nearby siblings), so it is largely complete.

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%, so the parameters are already documented, and the description's note about allVersions history being large largely restates the schema's own warning. The screenId-vs-componentId clarification adds marginal value, making this baseline-3 with a small lift.

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?

States a specific verb and resource (fetch a screen's generated HTML) and pins the scope to the currently-shown version. It clearly separates itself from the design-family siblings by citing the design handoff and the design-run check, though it does not address other siblings like screenshot or list_components.

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?

Explicitly states when to use this tool (build handoff) and when not to (checking whether a design run worked), and points to allVersions for history. The alternative path and the disqualifying condition are both spelled out rather than inferred.

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