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

The annotations already establish that this is a read-only, non-destructive operation. Beyond that, the description adds genuinely useful context: the information is guidance rather than live availability, and it contains no pricing. That prevents the agent from overpromising real-time inventory or quotes and is exactly the kind of context structured annotations cannot express.

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?

It is a single compact sentence, with the scope restriction placed after the positive statement, where it is easy to find. The phrasal structure ('Vehicle capacity and large-luggage guidance in a supported country'), which omits the verb, is the only weakness, but it is clear and has no filler.

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 tool that has one parameter, complete schema coverage, and read-only annotations, this description covers what the tool returns at a high level. There is no output schema, so a hint about the shape of the vehicle data would help; even so, nothing essential to correct invocation 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 schema fully documents the single `country` parameter, including how to obtain a valid slug, and the description adds nothing on top of that. With 100% schema coverage and no formatting, validation, or example detail in the description, the baseline score 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?

The description names a specific resource: vehicle capacity and large-luggage guidance for a country. That is concrete enough to distinguish it from its siblings, and the clause 'no live inventory or price' further separates it from the quote-related tools. It lacks an explicit verb such as 'list', which keeps it short of a 5, but the purpose is clear.

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?

The negative boundary ('no live inventory or price') implies where the tool does not apply, which helps callers route away from `get_charter_quote_instructions`. However, the description never states a positive trigger, such as 'call this after list_charter_countries when the user needs luggage or capacity details', so the agent has to infer the when-to-use condition.

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