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

Annotations already cover the safety profile (readOnly, idempotent, non-open-world, non-destructive), so the bar is lower. The description adds genuinely useful behavior beyond that: the 20-result cap, that the cursor is tied to the filters, and that an empty result means no listing matches. Return format details are absent but not critical.

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?

Five short, front-loaded sentences, each carrying a distinct constraint (scope, required fields, dependency rules, pagination, empty-state). No filler and no repetition of the title.

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 14-parameter search tool with 21% schema coverage and no output schema, the description covers only a handful of fields and never explains filter-combination semantics, enum meanings, or how to interpret result ordering. An agent would need to guess at the meaning and behavior of most filters.

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 only 21% across 14 parameters, so the description should compensate heavily. It explains the purpose requirement, municipality-requires-district relationship, and rent_period semantics, but leaves price_min/max, bedrooms_min, net_area_min, typology, property_type, features, locale, and limit undocumented in both schema and description.

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 (search) and resource (currently published properties in Portugal) with a clear scoping mechanism ('exact structured filters'). The scope distinguishes it from a single fetch, but it never names or contrasts the siblings compare_properties/get_property/get_area_statistics, so it stops 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?

Provides conditional prerequisites (purpose required, municipality requires district, rent budgets require rent_period), which is real usage guidance. However, it offers no explicit when-to-use/when-not versus the three sibling tools, leaving the routing decision to inference.

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