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

Annotations already declare readOnlyHint=false, openWorldHint=true and destructiveHint=false. The description adds real value beyond that: it explains the non-destructive rationale (the card reaches no one and is editable in Booksy), clarifies it creates exactly one card, and states the authorization requirement (Cotlet API key with access to this app).

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?

Three short sentences, purpose front-loaded, no filler. The informality of 'It reaches no one' and 'runs without asking first' is slightly conversational but every clause carries signal (safety, reversibility, auth), so it stays efficient.

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 simple 4-parameter, single-required-field create tool with no output schema, the description covers purpose, safety profile, authorization, and scope. Nothing critical is missing; only a hint about identifier/format expectations or duplicate handling would make it fully exhaustive.

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% and each property (name, note, email, phone) already carries its own description, so the schema does the heavy lifting. The description mirrors this by noting name is required and phone/email/note optional but adds no format, validation or syntax detail beyond the schema. 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?

The description opens with a specific verb and resource: 'Add a client card to your client list,' and immediately scopes it to a single card with name plus optional phone, email and note. This is unambiguously distinct from booksy_get_client and booksy_list_clients in the sibling set without opening any 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?

It gives a form of usage guidance by explaining that the action 'reaches no one' and the card is editable, therefore it 'runs without asking first' – a useful autonomy signal. However, it never states when to prefer this over alternatives (e.g. when a client is just a lookup) or any preconditions, so usage is implied rather than spelled out.

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