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

Beyond readOnlyHint/idempotentHint, it discloses non-obvious behavior: the entire set of 13 guides returns in a single unpaginated response, each entry contains title, cities, route slug and page URL, and a slug request produces full text, sections and FAQs. With no output schema present, this return-shape disclosure is exactly what the description must carry.

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 sentences, each doing distinct work: scope, return contents, slug mode, then usage and alternatives. Front-loaded with the listing behavior and closed with the sibling routing, with 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?

Complete enough to select and invoke correctly: scope, return shape, alternative tools and slug behavior are all covered. A small residual gap is that the error case for an unknown slug lives only in the schema, not the description, but nothing blocking is missing for a one-parameter read-only tool.

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 the baseline is 3; the description earns above that by explaining what passing a slug actually yields (that guide's full text, sections and FAQs) rather than just restating the field name. The error behavior for an unknown slug is disclosed in the schema rather than the description, so it is not double-counted here.

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 (lists published travel guides), quantifies scope (currently 13), and explicitly rules out pagination and filtering. It also clarifies the dual mode — bare call lists, slug call returns full guide text — and names the siblings it is not (search_routes, get_route_details).

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 when-to-use cases ('questions about driving time, border documents and what to expect on the road') plus an explicit exclusion routing pricing and booking to search_routes and get_route_details. The omit-vs-pass slug condition is also spelled out.

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