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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=true, so the safety profile is covered. The description adds no behavioral context beyond the size list — it never mentions that resizing reflows the 8-column grid and can displace neighboring widgets, nor whether the change is undoable (though undo_change exists) or what permissions are needed.

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?

A single tight sentence with no filler and the outcome stated up front. It loses a point only because its content largely duplicates the enum already enumerated in the schema rather than spending that sentence on information the agent lacks.

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 only three parameters, full schema descriptions, and annotations present, the definition is minimally sufficient to make a correct call. It is thin on layout side effects and on the overlap with update_widget, which are the two things an agent would most want to know before invoking it.

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 the schema itself is richer than the description, spelling out grid dimensions per size, phone behavior, and how to obtain widget_id and page. The description merely restates the enum values already defined in the schema, adding no meaning of its own. Baseline 3.

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 title plus description make the verb (resize, phrased as 'make ... small/wide/tall/large/banner') and resource (widget) unmistakable, and the enumerated sizes convey the transformation precisely. It does not, however, distinguish itself from the sibling update_widget, which an agent might reasonably expect to also change a widget's size.

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 when-to-use framing at all: nothing says to prefer resize_widget over update_widget for size changes, nor that the widget must already exist and be identified via get_page. The agent must infer the selection rule from the name alone.

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