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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds real value beyond them by disclosing catalog scale (~2.8 million hotels), the dual-mode behavior, and the fact that no date input is required. It says nothing about result ordering or how to page through such a large catalog, which is the remaining behavioral gap.

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 short sentences, front-loaded with the dual output mode, then scale, then the follow-up action. Every sentence contributes distinct information 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?

With an output schema present and full parameter coverage, the description covers the essential facts an agent needs: the two result shapes, scale, and the slug handoff to browse_hotels. The one omission is guidance on limit/pagination strategy given the very large result space, which matters for correct invocation.

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 100%, so limit, country, and language are already documented, including that country accepts a slug or ISO code and switches the output to places. The description restates that same country-switch behavior without adding syntax or format detail beyond the schema, so the baseline 3 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 states precisely what is returned in both modes: countries with hotel counts, or, when a country is supplied, the places within that country with counts. It also names the downstream consumer (browse_hotels), which separates it from hotel-search siblings. The action verb is only implicit ('Countries with their number of hotels'), which keeps it just short of a 5.

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 concrete next-step guidance ('Use the returned slugs with browse_hotels') and rules out a common misuse case with 'No travel dates needed', implicitly contrasting with date-driven hotel search. It does not explicitly state when to prefer a sibling like search_hotels over this tool, so no full when/when-not pairing.

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