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

Annotations only declare this is a non-read-only, non-idempotent, non-destructive write. The description adds real context beyond that: phone/email are stored in the customer's Contact record, a specific minimum-identity requirement applies, the response includes the new customerID, and the backing endpoint is POST /Account/{accountID}/Customer.json. It does not warn about duplicate creation despite idempotentHint=false, which keeps it from a 5.

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 tight sentences: what it does, the minimum input contract, then the return value and endpoint. Nothing redundant, no restating of the title, and the constraint is front-loaded where an agent will see it.

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?

With 8 optional parameters, no output schema, and sparse annotations, the description covers the essentials: minimum identity requirement, return shape (customerID), and the transport endpoint. It stops short of describing behavior on widely variable fields or duplicate handling, but that is a minor residual gap for a simple create.

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 per-field meanings are already documented and the baseline would be 3. The description earns extra credit by stating the cross-field constraint (at least one of first name, last name, or company) and the Contact storage grouping for email/phone — semantics that exist in neither the schema nor the required-parameter list (required is empty).

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 and resource ("Create a new customer") and immediately distinguishes itself from the get_/list_/update_ siblings by describing the write outcome. It also names the returned identifier (customerID), so an agent knows exactly what the call produces.

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?

Usage is implied by the verb and by the precondition "Give at least a first name, last name or company," which tells the agent what input is required. However, it never says when to use this versus looking up an existing customer first (lightspeedrseries_get_customer / list_customers), which matters for an insert operation that is not idempotent.

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