get_profile

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 real value beyond that by disclosing a data-coverage limitation: records only exist if Garmin itself recorded them, so watchless races or pre-device history will be absent. This is exactly the kind of caveat an agent needs to avoid over-claiming.

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 short sentences: what it returns, when to use it, and the one caveat that changes interpretation. Front-loaded with the payload and no 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 no parameters, an output schema, and annotations covering the safety profile, the remaining burden is the domain caveat, which the description handles well. The only gap is that it says nothing about behavior when no device or data is present, a plausible case for 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?

The tool takes zero parameters, which sets the baseline at 4. Schema coverage is 100% and an output schema exists, so there is no parameter semantics for the description to carry.

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 first sentence names the resource and its contents concretely: 'Fitness profile: VO2 max and personal records.' That is more specific than the sibling names alone (get_fitness, get_fitness_trends, get_progress), though the description never explicitly contrasts itself with those siblings, so an agent must infer the boundary.

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 gives an explicit positive directive — 'Use this instead of asking the user for their PBs' — which tells the agent when to reach for it rather than prompting the user. It does not name a competing sibling tool or state when-not-to-use, so it stops short of full routing guidance.

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