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

Annotations already establish that this is a safe, read-only, idempotent, closed-world read, so the description is free to add domain context — and it does: the onSale vs buildYourOwn distinction, and the fact that apart from onSale nothing carries a price or departure date. That's exactly the kind of non-obvious behavioral fact annotations cannot convey.

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?

Front-loaded with the one-line purpose, and the length is largely justified because there is no output schema to carry the return-value documentation. It loses a point for redundancy: the sport list '(cricket, golf, rugby, playing tours)' is enumerated twice and the middle sentence is a long multi-clause run that is harder to parse than it needs to be.

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 zero parameters, no output schema and no nested objects, the description carries the full burden of explaining what comes back — and it does, naming the onSale, buildYourOwn, sportHubs, countries and destinations keys plus the sport coverage within countries. Nothing an agent needs before calling 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?

The tool takes no parameters, so there is nothing for the description to disambiguate and the baseline is 4. The description instead spends its words on return structure, which is the right allocation.

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 ('List where Follow On Tours goes and what it sells there') and immediately distinguishes itself from siblings by naming list_tours and list_golf_trips as the places to go for prices and golf. An agent can identify this as the catalogue/coverage tool without opening any 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?

Explicit trigger is given: 'Use this when asked where Follow On Tours goes, or whether they cover a sport, a country or a ground.' It also states the complementary case — use list_tours for prices and details, list_golf_trips for golf — so the boundary between this tool and its siblings is unambiguous.

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