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

With annotations already declaring readOnly, idempotent, and closed-world, the description adds meaningful behavior: which fields come back, the century ambiguity, that omocodia is reported, and that failures return a reason distinguishing format errors from check-character errors. It does not mention output shape or how the two-century case is represented, which is the main remaining gap.

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?

Three tightly packed sentences, front-loaded with the returned fields, followed by the key limitation and the failure mode. No filler; each sentence adds distinct information.

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?

No output schema exists, so the description must convey return content, which it does by enumerating every decoded field plus the error behavior. What is missing is the concrete return structure and how ambiguous centuries/omocodia are encoded in the response.

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 'code' parameter already documents format, length, and accepted lowercase/spaces. The description adds no syntax or handling detail beyond that, so the schema carries the full parameter burden.

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 and resource ('Read back a codice fiscale') and immediately enumerates the decoded fields, so the agent knows exactly what it gets. The inverse relationship to compute_codice_fiscale (and the distinction from verify_codice_fiscale) is clear from the decode framing.

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?

Implied usage is clear: use this to extract information from an existing code, not to validate-only or generate one. It does not explicitly name compute_codice_fiscale or verify_codice_fiscale as alternatives, nor state when to prefer them, so routing is inferred rather than spelled out.

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