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

Annotations already declare non-destructive, idempotent writes, and the description usefully adds reversal semantics and the fact that ordering of testimonial_ids is preserved when pinning. It doesn't disclose permission requirements or what a partial failure across up to 200 ids looks like, which keeps it below 5.

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?

Two sentences, front-loaded with the primary action and followed by the reversal rule. No filler and no repetition of the title.

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?

For a 4-parameter mutation tool with no output schema, the description covers the action, the optional pin step, ordering, and undo. The remaining gap is the exact role of pin_to_widget_id and the response shape, but nothing critical to invoking it correctly is missing.

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 only 25%, so the description must compensate, and it does: it clarifies the two boolean toggles (favorite default true, unpin) and that array order is meaningful. It leaves pin_to_widget_id implicit rather than stating whether it is required for pinning or what happens when omitted.

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 specific verbs (star/favorite, pin) against a specific resource (testimonials, to the top of a widget), plus the reversal actions. It is clearly distinguishable from siblings like tag_testimonials or moderate_testimonials, which mutate different attributes.

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?

It explains the conditional nature of pinning ('optionally pin them') and gives explicit undo instructions ('Set favorite=false or unpin=true'), which tells the agent how to reverse each effect. It does not name alternative tools or state when-not-to-use it, so it falls short of a full 5.

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