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

Annotations already cover read-only/idempotent safety, so the bar is lower; the description still adds genuinely useful behavior: the shape of the result (rank order, guide URLs, coordinates, other categories, citation) and, most importantly, that a country/category with no list returns an error naming the valid ones. It stops short of documenting pagination or rate limits, which are not obviously relevant for a fixed 10/20-item list.

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?

Four dense sentences, front-loaded with the scope and routing before the return shape and edge case; every clause carries information. The return-value sentence partially duplicates the existing output schema, which is the only slack in an otherwise tight definition.

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?

Covers scope, routing, cardinality, error behavior, and the result shape. With an output schema present it does not need to detail return values, and it does not pad with them beyond a brief orientation. An agent has everything needed to call it correctly on the first try.

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%, so baseline is 3; the description adds meaning beyond the schema by explaining the cardinality consequences of each parameter combination (20 worldwide vs 10 per country, overall vs within one category). It does not add syntax or format guidance beyond what the schema descriptions already provide.

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+resource ('List Meridian Dispatch's ranked World's Best places') and immediately bounds the scope (20 worldwide or 10 per country, overall or per category). It explicitly names the siblings it is not (get_destination, list_nearby, search_guides), so an agent can route without opening another 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?

Gives concrete trigger phrases ('top things to do in X', 'best beaches in X') plus three explicit alternatives with the conditions that select each: get_destination for one town, list_nearby for proximity, search_guides for anything else. Nothing 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.