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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds value by disclosing return content (counts per country, localized names), which goes beyond the annotations. It does not discuss response size or caching, which would be the only remaining 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?

Two sentences, front-loaded with the 'Use this when...' trigger, with zero filler. The second sentence is slightly dense as a list, but every clause names a distinct category the tool returns.

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, return structure need not be explained, and the description still summarizes payload contents. A single optional parameter and rich annotations close the remaining gaps; only latency or catalog volatility notes are absent.

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%: the locale parameter is fully documented with an enum and a description. The phrase 'named in the requested language' restates what the schema already says, so the description adds little parameter-level information beyond the baseline.

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 (search catalog) and enumerates exactly what it contains: countries with counts, property types, transaction types, features, sort orders and currencies. It is clearly a reference/lookup tool, distinguishable from search_listings, which actually performs searches.

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 states concrete triggers ('when the user asks in which countries new.estate has listings or which property types and features can be searched') and an explicit sequencing rule ('check filter values before search_listings'). The alternative sibling is named, along with the condition that selects it.

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