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

Annotations already establish readOnlyHint=true and destructiveHint=false, and the description does not contradict them. It adds useful context about the data being self-reported series with units, but it does not disclose any additional behavioral details such as ordering, pagination, or scope beyond the user's metrics.

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 names the operation and immediately clarifies the resource with helpful examples and the unit concept. Every element earns its place; there is no repetition or 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?

For a parameterless read-only report with an output schema and safety annotations, the description gives enough to know what the tool returns. It is slightly incomplete only in the sense that it never addresses the near-twin sibling get_custom_metrics, which is a selection rather than invocation gap.

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 accepts zero parameters, so the baseline is 4 and there is nothing for the description to clarify beyond the general scope. The empty schema and 100% schema coverage mean parameters cannot be a gap.

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 clearly states the operation (list) and the resource (the user's custom metrics), and it adds a concrete sense of what those metrics are (self-reported series like pushups or weight history, each with unit). It does not explicitly differentiate from the similarly named sibling get_custom_metrics, so it loses the top point.

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?

There is no guidance on when to use this tool versus its siblings, particularly get_custom_metrics or list_daily_metrics. The context is implied by the name and short description, but no exclusions or alternative routing are provided.

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