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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, covering the safety profile. The description adds valuable behavioral context beyond annotations: the exact payment requirement ('x402 payment of 0.02 USDC on Base Mainnet per call') and the fact it uses official/public sources. This goes beyond the structured fields and helps the agent understand side effects and prerequisites. It does not contradict any annotation.

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?

The description is somewhat long but every sentence adds value: purpose, sources, identifiers, return fields, use cases, availability, and payment. It is front-loaded with the core purpose and then details. No filler or redundancy; the structure is logical and readable. It earns a 4 for being informative without being bloated.

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?

Given there is no output schema, the description compensates by enumerating the return fields ('normalized identity, status, legal form, address, NACE/ATECO, source timestamps and VAT verification'). It also covers payment, use cases, and the read-only nature. It lacks explicit error handling or not-found behavior, but for a single-parameter read-only tool with rich annotations, this is sufficient. It is nearly complete for an agent to call it correctly.

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?

The schema has 100% coverage with a description for the only parameter 'identifier' that already explains it can be Codice Fiscale, Partita IVA (optionally prefixed with IT), or LEI. The tool description repeats this information without adding new details like format specifics or examples. Since the schema carries the full semantic load, the description adds no extra value beyond what the schema provides, so the baseline of 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?

The description clearly states the tool's purpose: 'Italian company registry lookup, verification and KYB pre-check'. It specifies the exact sources used (Registro Imprese / InfoCamere HVD, VIES, GLEIF, OpenCoesione, AGCM), the search identifiers (Codice Fiscale, Partita IVA, LEI), and the return fields. It is a specific verb+resource description that fully distinguishes the tool's function, even without siblings.

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?

The description provides clear usage context: 'For supplier verification, procurement, due diligence and compliance.' It also states it is read-only and requires payment per call, which helps an agent decide if it's appropriate. However, it does not explicitly state when not to use it or mention alternatives, but with no siblings that is acceptable. The guidance is clear and actionable.

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