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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely useful non-obvious context: this connector never books, pays or sends messages, so the agent should not expect any side effect or write path. It doesn't mention pagination or rate/visibility limits on the public profile.

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 sentences, zero waste, and front-loaded: the return contents come first, the action boundary second. Every clause earns its place by telling the agent what it receives and what it cannot do.

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 carries the burden of describing returns, and it does so thoroughly (profile fields plus plan price and billing period). Combined with the explicit note that the profile_url page handles contact and signup, an agent has everything needed to call and interpret this 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% and the single parameter is documented in the schema as the trainer id returned by find_trainers. The description adds no syntax, format or validation detail beyond 'one personal trainer', so the baseline of 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 and resource ('Show the public profile of one personal trainer from the Trainer Connect directory') and enumerates the concrete contents returned (bio, specialties, work location, online/in-person, published plans with price and billing period). The word 'one' implicitly distinguishes it from the sibling find_trainers, which searches the directory.

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 clear context for use (retrieving a single trainer's public profile) and draws an explicit when-not boundary: booking, paying and messaging never happen here, they happen off-connector via profile_url. It stops short of stating the prerequisite that the trainer id must first come from find_trainers, though the schema covers that.

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