garmin_whoami

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

The annotations already declare this as read-only and open-world, so the safety profile is covered. The description adds minor behavioral context by specifying that it returns account identity and unit preferences, but it does not disclose any potential edge cases or additional behaviors beyond that.

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 a single, tightly worded sentence with no filler. It front-loads the action and resource, making it immediately scannable for an agent.

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 zero-parameter, read-only identity tool with an output schema and no side effects, this description is complete. The agent has everything needed to invoke it correctly: no inputs, a clear purpose, and the safety profile already provided by annotations.

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?

There are zero parameters, so the parameter-semantics burden is minimal and the baseline is 4. The description correctly conveys that the tool needs no input, and mentioning the account and unit preferences as the subject is sufficient for a no-argument call.

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 uses a specific verb ('Identify') and clearly names the resource: the signed-in Garmin account and its unit preferences. This uniquely distinguishes it from the long list of sibling tools, which all target specific data types rather than the current user identity.

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?

The intended use is implied by the tool's name and description: call it when you need to know who is signed in or what unit preferences are active. However, it does not explicitly state when to use it versus alternatives or mention any prerequisites, so the guidance is left to inference.

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