Create SdI / FatturaPA Invoice (XML)

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

Annotations indicate a write operation (readOnlyHint=false) with possible external side effects (openWorldHint=true). The description adds substantial context: it creates a compliant XML document, can submit to SdI, requires a specific plan, and returns either an XML string or JSON with UUID. It also discloses supported invoice types and customer-specific requirements, all consistent with the annotations.

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 well-structured: a lead sentence, a 'Key facts' bullet list, a 'Returns' line, and an 'Args' section. It's moderately lengthy but every section serves a purpose given the tool's complexity, and it avoids repeating schema details verbatim.

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 explicitly states return values ('XML document string when not submitting, or JSON with UUID when submitting') and covers generation, submission, integration options, and plan requirements. Minor omissions like explicit error conditions do not significantly impact completeness for this complex tool.

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%, so the schema already documents all parameters. The description adds semantic constraints beyond the schema: e.g., 'For Private customers: sdi_type must be ''0000000'' and tax_id_code (codice fiscale) is required', 'For PA customers: use version=''FPA12'' and the 6-char PA office code as sdi_type', and VAT rates with nature code required at 0%. These enrich parameter understanding beyond the structured fields.

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 'Generate an Italian FatturaPA electronic invoice in XML format and optionally submit it to the SdI', which states a specific verb, resource, and scope. This distinguishes it from sibling tools like pop_create_ksef_invoice (Poland) or pop_create_zugferd_invoice (Germany) by explicitly targeting Italian FatturaPA e-invoicing.

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: Italian e-invoicing compliance (D.Lgs. 127/2015), support for B2B/B2C, customer types, and the Growth+ plan requirement for SdI submission. However, it does not explicitly name alternative tools or state when not to use this tool, so it falls short of full exclusionary guidance.

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