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

Annotations already cover read-only/idempotent/non-destructive, so the bar is lower, and the description adds real value: it says you get back that page region with a few surrounding lines plus the matching OCR text, warns that omitting 'area' returns the whole page which is poorly readable, and notes that a shorter excerpt yields a larger, more legible crop. It also instructs the agent to attribute the reading to the scan rather than to the OCR. Only the exact response shape remains implicit.

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-loaded with purpose, then usage, then both calling modes, then caveats — a sensible order. It is on the long side, but nearly every clause adds decision-relevant information (excerpt-size/legibility tradeoff, coordinate range, attribution rule).

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 4-parameter tool with no output schema and 0% schema coverage, the description explains the return content, both input modes, and the cost/legibility tradeoffs, which is enough to call it correctly. Minor gaps: the formats accepted by fonte_id and fascicolo are not spelled out.

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 0%, so the description must carry the load and largely does: it explains the two calling modes (fonte_id of a passage, or fascicolo + pagina with an area box), gives the area range 0-10000, and notes what happens when area is omitted. It leaves the accepted format of fonte_id and fascicolo unspecified, which is the remaining gap.

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?

Opens with a concrete verb+resource: 'L'immagine della pagina originale', to check an OCR-doubtful spot. It immediately distinguishes itself from nearby siblings, noting that 'verify_quote controlla solo l'OCR' and that it is not for reading whole pages, so an agent can pick it without opening other schemas.

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?

Explicit triggering conditions: a name, surname, date, figure or meaning-bearing word is garbled, odd or decisive, or the lines look mixed across columns. It also states when NOT to use it ('Non serve per leggere pagine intere', 'né per ogni brano') and routes OCR-only verification to verify_quote.

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