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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds useful non-annotation context: the catalog is 1,000+ entries and responses are truncated at `limit`, explaining why filtering matters. Minor gap: no explicit note on paging combination or rate limits.

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?

Two tight sentences: the scoping/size constraint and filtering guidance are front-loaded before the endpoint reference. Every clause earns its place with no repetition of the title.

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 helpfully enumerates returned fields and discloses the volume and cap on results, which is enough for an agent to call it correctly. It leaves offset/paging interplay to the schema, a minor omission for a filtered-list tool.

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% (limit range/default, offset paging, search matching, country ISO code), so the schema already carries parameter meaning. The description restates filtering behavior and the response cap but adds no syntax or format 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?

States a specific verb (list) and resource (couriers/carriers TrackingMore supports) and enumerates the returned fields (courier_code, name, country, website, phone, extra fields). This is clearly distinguishable from siblings like detect_courier, which resolves a courier for a tracking number, and from the tracking CRUD tools.

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?

Gives concrete operational guidance: because the full list exceeds 1,000 entries, filter with `search` and/or `country`, and each reply is capped by `limit`. It does not explicitly contrast with detect_courier or say when not to call it, so it falls short of a full when-to-use/alternative statement.

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