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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), so the bar is lower; the description still adds real behavioral context by disclosing cost ($0.10), an API-key requirement, and the trip-status filter that governs what is returned.

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 tightly packed clauses with no filler; the scope constraint is front-loaded and the operational caveats (cost, auth) trail appropriately. Dense but every clause carries information.

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, return values need not be described, and the inclusion rules plus cost/auth caveats are well covered. The gap is the two undocumented parameters, which leave the range arguments entirely unexplained.

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 0% for the two parameters (to, from) and the description never mentions them or their expected format, so an agent gets no added meaning about the range semantics beyond the bare names.

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 a specific resource (canonical cities) and its derivation scope (confirmed/completed trips only), which lets an agent distinguish it from the coarser get_countries_visited. It never says plainly that it returns a list, but the resource and scope are unambiguous.

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 gives inclusion/exclusion rules ('excludes soft pins / status=possible') and a data-derivation precondition (category=travel + structured location), which implies when the tool is populated. However it never names an alternative such as get_countries_visited or get_travel_history, nor states when to prefer this over them.

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