Add a client

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

With no annotations, the description carries the full behavioral burden. It discloses the non-obvious upsert behavior, that re-adding the same name overwrites address, email, and VAT id, and that an identical record is refused with the existing id named. Auth and return-value details are absent, but the mutating and overwrite semantics are clearly surfaced.

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?

Two sentences with no filler: the first front-loads the purpose, and the second gives exact update and refusal semantics. Every sentence contributes non-schema information.

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 four-parameter tool with no annotations and no output schema, the description covers the essential call semantics: purpose, identity key, upsert behavior, and duplicate handling. The main omission is the success return value, but that is not critical because downstream invoice_create refers to clients by name.

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?

Only 25% of parameters are described in the schema, so the description compensates by establishing 'name' as the lookup key and identifying address, email, and vat_id as the fields updated on re-add. It does not provide formats or constraints for email/address, but the essential parameter semantics for calling the tool are present.

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 states a specific action ('Store a client'), the resource, and the downstream purpose: enabling invoice_create to refer to the client by name. This clearly differentiates client_add from sibling tools like client_list and client_delete.

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 gives clear context on when to use the tool: before creating an invoice that needs to reference a client by name. It does not explicitly state when not to use it or name alternative tools, so it falls just short of fully explicit routing.

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