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

Annotations already establish WRITE semantics, non-destructive behavior, non-idempotency, and open-world scope. The description adds useful behavioral context by clarifying that nothing is sent to the contact and by naming the POST /contacts endpoint.

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 description is three short sentences, front-loads WRITE, and has no redundant or wasted phrasing. It communicates purpose, minimum input, side effect, and endpoint efficiently.

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 many optional fields, the description covers purpose, minimum input, side effects, and endpoint while annotations cover safety and open-world behavior. It does not describe the response, but no output schema exists and the key invocation constraints are present.

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 100%, so the schema already documents all 16 contact fields. The description still adds meaningful semantics by stating a minimum requirement of at least a name, company, or number, which the schema itself does not enforce via required fields.

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 verb and resource: create a contact in the shared Placetel phone book. It clearly distinguishes creation from sibling operations like get_contact, list_contacts, and update_contact.

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 clear creation context and a minimum data requirement: at least a name, company, or number. It does not explicitly route away from update_contact for existing contacts, but the create-vs-update distinction is clear from the verb and sibling name.

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