Your devices

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

The readOnlyHint and openWorldHint annotations already establish the safe read-only nature. The description adds useful behavioral context by specifying that results are account-scoped and ordered by most recent sync. With an output schema present, no additional return-format disclosure is needed.

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?

A single, front-loaded sentence conveys the action, resource, scope, and ordering with no filler. The title is slightly redundant but the description itself is optimally concise.

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 listing tool with an output schema, the description fully covers what an agent needs: what is listed, whose devices, and the order. No additional prerequisites, auth notes, or side-effect warnings are relevant.

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 input schema has zero parameters, so there is nothing for the description to clarify about arguments. The baseline of 4 applies; the description appropriately focuses on the operation and result ordering instead.

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 ('List'), a clear resource ('Garmin devices'), and the account scope, plus an ordering detail ('newest sync first'). This clearly distinguishes it from the many sibling tools focused on activities, metrics, and 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?

The description makes the use case plain: retrieve the account's registered Garmin devices. It does not explicitly name alternatives or exclusions, but the tool's scope is clear enough that an agent can infer when to select it over the metric-focused siblings.

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