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

Beyond the read-only and idempotent annotations, the description discloses important behavioral caveats: qualifications and insurance are self-reported and must be repeated as such, and 'verified' only means identity documents were checked. It also states that phone and email are unavailable and directs users to the enquiry form, which is valuable operational context.

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 provides return fields, caveats, and contact limitations in a logical order. It is somewhat long, but nearly every sentence adds useful guidance rather than repeating structured fields.

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?

There is no output schema, so the description appropriately lists the returned profile fields and explains important interpretation caveats around qualifications, insurance, and verification. Together with the clear parameter guidance and annotations, it gives an agent enough to call and interpret the 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 description coverage is 100% and the single username parameter is already documented in the schema. The description adds meaningful semantics by explaining that the username comes from search_trainers or the last segment of a profile URL, with an example URL format.

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: get the public profile of one personal trainer by username. It also distinguishes this from the sibling search_trainers tool by explaining that the username comes from search results or a profile URL.

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 clearly explains how to obtain the username from search_trainers or a profile URL, which gives strong usage context. It does not explicitly state when not to use this tool, but the single-profile scope is unambiguous.

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