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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real value beyond that by disclosing output behavior: which overlapping UI element is reported and that a nearest-clearing position is suggested. It stops short of stating what is returned when there is no overlap.

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?

Three sentences, front-loaded with the core check, followed by the reported outcome and the coordinate convention. Every sentence carries information an agent needs and there is 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?

With no output schema, the description does the work of explaining the two return components and the 'all' platform option is spelled out in the schema. Only the no-overlap case and the boundary of the comment-sticker option (already in schema) are unaddressed, which is minor for a read-only validation tool.

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 all eight parameters including the platform enum and the comment-sticker band are already documented. The description only restates the pixel/top-left coordinate convention and clarifies that the box represents a caption, title or logo — marginal added meaning, so the baseline 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?

States a specific verb and resource ('Checks whether a rectangular text box ... stays inside the safe zone'), names the four platforms, and describes the two-part outcome (overlap report + suggested position). An agent can distinguish this from get_safe_zone, which by name returns zone geometry rather than validating a specific box.

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?

Usage is implied by the description (validate a caption/title/logo rectangle before export), but there is no explicit when-to-use or when-not-to-use guidance and no reference to get_safe_zone or export_settings as alternatives. Nothing is misleading, but the routing decision is left to inference.

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