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

Annotations already declare the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), so the lower bar applies. The description adds genuinely useful behavior beyond that: the fallback `dato non disponibile` on small samples and the explicit instruction to quote no figure in that case.

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?

Front-loads purpose, then usage, then the failure mode — good ordering with no filler. The content is duplicated verbatim in Italian and English, which doubles length but serves bilingual discovery rather than padding.

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 for this complexity: annotations carry the safety profile, an output schema covers the return shape, and the description adds the one thing structured fields don't convey — the no-data fallback and the instruction to withhold figures. Nothing needed 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%, so both `citta` and `mq` are already documented with format examples and bounds. The description only implies the unit-size dimension ("per misura del box") and adds no syntax or constraint beyond the schema — baseline 3 is appropriate.

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 ("legge"/reads) and resource ("l'ultimo indice dei prezzi del self storage") scoped to an Italian city, plus the exact dimensions returned (min, median, max by unit size, sample counts, month). This is clearly a price-index lookup, distinct from the centre-search siblings, though it never names them for explicit contrast.

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 an explicit trigger ("Usalo per rispondere a «quanto costa un box a…»") and a clear when-to-skip rule for the small-sample case. It stops short of naming the alternative tools (cerca_centri, dettaglio_centro) for the "find a unit" intent, so no real exclusion map.

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