update_cashbook_entry

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

Only idempotentHint is annotated, so the description carries most of the behavioral burden; it does usefully disclose the patch/merge behavior (unchanged fields are preserved by omission). It says nothing about validation, whether changing amounts recalculates totals, or what the response contains, which matters for a mutation tool with no output schema.

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?

A single short sentence with the action front-loaded and zero filler. It is efficient, though the terseness borders on under-specification for a tool with a nested untyped payload.

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 nested free-form `data` object, no output schema, and only an idempotentHint annotation, the description is too thin: it omits the valid field set, how the entry is identified/validated, and any error or side-effect behavior. An agent could invoke it but would have to guess the payload shape.

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 33% and the critical parameter `data` is a free-form object with additionalProperties {} and no property descriptions. The sentence clarifies that `data` is a partial patch, but it never hints at the accepted field vocabulary (amount, date, description, payment method, etc.), leaving the main ambiguity unresolved; `id` is also unexplained in the description.

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 gives a specific verb and resource ('Modifica un movimento di prima nota') and scopes the domain with '(incassi e pagamenti)', which clearly separates it from the sibling create_cashbook_entry / delete_cashbook_entry / get_cashbook_entry set. It does not explicitly name a sibling, so it stops short of a 5.

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?

'passa solo i campi da cambiare' conveys the intended usage pattern (partial/merge update rather than full replacement), which is real guidance. However, there is no statement of when to prefer this over a full rewrite, no prerequisites (existing entry, permissions, closed periods), and no warning about what happens to fields omitted.

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