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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered. The description adds real value beyond that: it states the call returns the new client's ID, that it runs without a confirmation prompt (because a client reaches nobody and can be deleted), and that a Cotlet API key with app access is required.

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 purpose is front-loaded and each sentence carries information (fields, return value, e-invoice handling, safety, auth). There is mild redundancy between 'Add a client' and 'Creates a client', but overall it is tight.

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 create tool with no output schema, the description covers the return value (ID), auth requirement, and confirmation behavior. Nothing critical is missing, though a pointer to update/get siblings would round it out.

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 schema already documents all seven parameters, including the optional company_id. The description only restates which fields are relevant, adding no format or syntax detail beyond the schema, so the baseline 3 applies.

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 ('Add a client') and resource, and enumerates the identifying fields (name, VAT number, tax code, address). An agent can distinguish this from the sibling fatture-in-cloud_list_clients without opening the 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 a clear condition: use this to create a client, and for e-invoices pass the e-invoice code or certified email. It doesn't explicitly name an alternative (e.g., list_clients for lookups), but the creation context is unambiguous.

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