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

readOnlyHint=true already tells the agent this is a safe lookup, and the description reinforces it by framing the result as redirect URLs. It adds no further behavioral context (no auth requirement, no note on whether the redirect is stable or locale-dependent), but for a trivial read-only resolver the annotations carry most of the burden, so a baseline-plus 3 is appropriate.

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 clipped labeled clauses (WHAT / RETURNS / USE) are front-loaded and waste no words. Every sentence — including the return-field enumeration and the exclusion — carries information an agent needs to pick and call the tool.

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?

Output schema exists so return values need not be described, yet the description helpfully names googleReviewUrl and canonicalUrl anyway. With annotations covering safety and the schema covering the only parameter, the definition is essentially complete; the only minor gap is any note on how locale influences the returned canonical URL.

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% and the single locale parameter's enum, default, and prefix semantics are fully spelled out in the schema itself (including that it does not affect prices or phone numbers). The description adds nothing about locale, 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 ('Short /review redirect to the Google review URL') and two concrete return fields, and explicitly rules out the confusable operation ('Not a list of existing ratings'). An agent can distinguish it from the surrounding get_* content tools without opening the schema.

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?

'USE when the user wants to leave a review' gives a clear positive trigger, and 'Not a list of existing ratings' provides a negative boundary. However, no sibling alternative is named (there is no reviews-list tool, but resolve_locale_url or list_locales could plausibly be confused context-wise), so it stops just short of a full when/when-not/alternatives treatment.

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