update_issued_document

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

The only annotation is idempotentHint=true, which the description is consistent with, and the text adds real behavior beyond it: patch-style semantics (only passed fields change), automatic numbering when `number` is omitted, and a tax-regime-specific rule. What is missing is the state-dependent behavior that matters most for this resource — whether an already-sent/electronic invoice can still be modified, and what happens to numbering if a number is supplied later.

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 the core action in the first clause, then layered with the highest-value caveats in descending priority; every clause carries information. Slightly dense, with an open-ended enumeration ("fattura, nota di credito, ... DDT...") that adds breadth but also length.

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 mutation tool with a free-form nested `data` payload and no output schema, the definition covers the critical mechanics (partial update, numbering, stamp duty) but leaves the editable-field vocabulary essentially undocumented. An agent knows how to call it correctly in shape, but may still have to guess field names and cannot tell which documents are locked.

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 only 33% — `id` and the free-form nested `data` object have no schema descriptions — so the description carries most of the burden and does so reasonably: it explains that `data` holds only the changed fields, that `number` inside it controls numbering, and that `stamp_duty` accepts a specific value for forfettari. The gap is that `data` is an unconstrained object and the description gives no hint about the broader set of accepted field names.

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 (Modifica) on a specific resource (documento emesso) and enumerates the document types it applies to (fattura, nota di credito, proforma, preventivo, ordine, DDT). It also distinguishes itself from duplicate_document by name, so an agent can separate it from its closest sibling without opening a schema.

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?

Gives explicit operating guidance: send only the fields to change (partial update), omit `number` to get automatic numbering, and use duplicate_document instead when the intent is to repeat an existing document. It even encodes a domain rule (stamp_duty: 2 for forfettari above 77,47 €) that would otherwise cause compliance errors.

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