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

Annotations already declare readOnly, idempotent, and closed-world, so the safety profile is covered. The description adds the useful fact that the response includes the contributor's posts, which is not in any structured field; error behavior for invalid handles is the only notable omission.

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 compact sentences plus an example, front-loaded with the core question. The example is useful rather than filler; the phrasing is slightly informal but not wasteful.

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?

For a single-parameter read with full annotation coverage and no output schema, this covers purpose, input source, and partial return content. It could say more about the shape of the returned contributor record, but nothing essential is missing.

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 0% (the handle field has no description), so the description must compensate, and it does: it identifies where the handle value comes from and gives a concrete JSON example of the expected 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?

Names a specific resource (GetFit contributor) and what it returns (profile plus their posts), so the agent knows this is a detail lookup rather than a listing. It is distinguishable from list_contributors, though it doesn't explicitly contrast with get_workout or search_workouts.

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?

Explicitly states the prerequisite: the handle must come from list_contributors. That routes the agent correctly, but no guidance on when to prefer this over search_workouts or what to do for an unknown handle.

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