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

Annotations already declare readOnly/idempotent/non-destructive, so the description correctly spends its words on behavior annotations cannot express: the two-phase Container → Address drill-down workflow, the US default for country_code, and which result types are order-eligible. It does not add rate-limit, auth, or result-count context, which keeps it short of 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 dense sentences, front-loaded with the core action and return shape, then the filtering detail, then the drill-down rule. No restatement of the name or 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 an output schema present and full parameter documentation, the description only needs to cover what structured fields cannot: the multi-step container drill-down and result-type validity. Both are stated, leaving nothing an agent needs in order to call and chain this tool correctly.

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 a 3 is the baseline and the schema already documents all four parameters. The description goes further by explaining how container and query interact across successive calls and by reinforcing the country_code default, adding cross-call meaning the schema cannot convey; target is left to the schema.

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 ('search for a mailing address') plus the concrete return payload ('Loqate suggestions with IDs'). An agent can immediately distinguish this lookup tool from the sibling order-creation tools (create_order_draft, pay_order, etc.).

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?

Explicit when-to-use and follow-up routing: pass country_code to filter, and if a suggestion has type 'Container', call this tool again with container=<id> to drill down. It also states the terminal constraint that only type 'Address' is valid for order creation, telling the agent when a result is usable and when it is not.

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