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

Annotations already declare read-only, idempotent, non-destructive, closed-world semantics, so the safety profile is covered. The description adds real value beyond that: it identifies this as a reference/lookup tool and explains the chaining contract (slug feeds other tools), which is behavioral context an agent needs.

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 tight sentences: the first front-loads what is listed and what is returned, the second covers the filter and downstream usage. No filler or repetition.

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?

An output schema exists, so return values need no further explanation, and the description still covers scope, filtering, and tool chaining. For a single optional-parameter list tool, nothing an agent needs to call it correctly 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?

Schema description coverage is 100% and the schema already documents the ISO code vs English name duality with examples. The description repeats the country-filter semantics ('NL' or 'Netherlands') without adding syntax or edge-case detail beyond the schema, so 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?

States a specific verb (list) and resource (cities where rental listing alerts are sent), plus the exact fields returned (slug, name, country). This is clearly distinguishable from siblings like get_plans or start_home_search.

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?

Explains the optional country filter and, more usefully, tells the agent to use the returned slug with check_city_supply and start_home_search, establishing downstream workflow context. It does not explicitly state when-not to use this tool or contrast it with get_plans, so it falls short of a 5.

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