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

Annotations already establish read-only, idempotent, non-destructive, and closed-world behavior. The description adds substantial behavioral context beyond that: what the return payload contains, how address_id relates to bookings/invoices, that past uncharged bookings are included, and that times are in the store's time zone.

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 front-loaded with the core purpose and then details the returned fields. It is somewhat dense and field-heavy, but every clause adds useful context and there is no filler.

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 no output schema, the description carries the full burden of explaining the response. It does so thoroughly, covering profile fields, addresses, booking counts, uncharged bookings, gift cards, referrals, and time-zone behavior.

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%, and the single customer_id parameter is documented in the schema as coming from list_customers. The description does not add further parameter-level meaning, so baseline 3 is appropriate.

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 clearly defines a single-customer retrieval and enumerates what is returned: contact details, addresses, booking counts, and not-yet-charged bookings. It distinguishes this from a list operation by saying 'One customer,' but does not explicitly name list_customers as the alternative.

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: fetch one customer by customer_id, likely after finding the ID via list_customers. However, there is no explicit guidance on when to use this instead of list_customers or create_customer, and no exclusions or prerequisite context beyond the schema.

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