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

Annotations already mark the tool as read-only, idempotent, and non-destructive, and the description adds valuable behavior beyond that: it returns two separate amounts, a liquidity impact, and FatturaPA instructions. It also discloses that the tool is free, deterministic, and requires no login, and it warns about the N6 code misuse, which is useful operational context.

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 dense but every sentence earns its place: purpose, mechanism, outputs, FatturaPA caveat, and cost/auth traits. There is no filler or repetition of the schema's parameter descriptions. Front-loading the purpose makes it immediately scannable.

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?

With no output schema, the description properly explains what the tool returns: two separate amounts, liquidity impact, and FatturaPA instructions. It also covers the key regulatory nuance (N6 not applicable) and the free/authenticated status, making the description self-sufficient for an agent to invoke the tool 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?

Schema description coverage is 100%, so the parameters are already fully documented in the schema. The description adds conceptual context around imponibile and IVA flow, but it does not add new format, default, or constraint details 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?

The description opens with a specific verb and resource: 'Calcola la scissione dei pagamenti' for forniture alla Pubblica Amministrazione, backed by the legal reference art. 17-ter DPR 633/72. It also distinguishes itself from reverse charge by explicitly stating that Natura N6 codes belong only to reverse charge, which differentiates it from the calc_reverse_charge sibling.

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 clearly states when to use the tool: for supplies to the PA under split payment rules. It also gives a meaningful exclusion by noting that N6 codes are not used here and belong only to reverse charge, implicitly steering agents away from this tool for reverse-charge scenarios. It stops short of explicitly naming calc_reverse_charge as the alternative, so it is not a full 5.

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