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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral value beyond that: it discloses the return shape (results with id/title/URL) and the two-step retrieval pattern ('il testo si legge con fetch'), plus the scoping boundary that it does not resolve addresses.

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?

Purpose is front-loaded in the first clause, followed by the corpus list, the return shape, and the sibling exclusion. The middle enumeration is dense but each item maps to a real content domain, so it earns its place; only slightly long.

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 single-parameter search tool with an output schema present, this is essentially complete: corpus scope, return shape, and the alternative tool are all covered. Minor omissions such as result limits or pagination behavior are not material given the output schema.

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% and the single query parameter is already documented with examples, so the baseline is 3. The enumeration of indexed content domains adds indirect help in formulating queries, but it does not add syntax or format detail beyond what the schema provides.

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 verb (Cerca) and enumerates the exact corpus it covers: prices, conditions, home/business price lists, coverage, activation, payments, assistance, company info, and the Open Fiber voucher. It also distinguishes itself from the sibling verifica_copertura in the same breath, so an agent can separate the two without opening a schema.

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 an explicit when-not and names the alternative: 'Non verifica un indirizzo: per sapere cosa arriva a un civico usa verifica_copertura.' That is a direct routing rule to the correct sibling, which is exactly what usage guidance should do.

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