query_activity_metrics

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

Annotations declare readOnlyHint=true, which aligns with 'Get activity metrics'. The description adds context about available metrics but does not disclose other behavioral traits like data availability, pagination, or error handling. With annotations present, this is acceptable but not exceptional.

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 concise and front-loaded: three sentences covering purpose, included metrics, and usage of the metrics parameter. No unnecessary words or repetition.

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?

Given an output schema exists (context signal), the description covers the tool's purpose, available metrics, and parameter usage. It does not mention data granularity or time zones, but these are less critical for a query tool with a well-defined schema. Overall, it is sufficiently complete.

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 100%, so all parameters have descriptions. The description adds marginal value by reinforcing the default metrics and their selection, but does not provide new semantic meaning beyond what the schema already offers.

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 tool retrieves activity metrics and lists specific metrics (steps, stress, respiration, etc.). It distinguishes from sibling tools like 'get_activity_details' or 'query_heart_rate_data' by focusing on a broad set of activity metrics.

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 implicitly indicates usage by saying 'Select specific metrics to retrieve using the metrics parameter' and shows default metrics. However, it lacks explicit guidance on when to use this tool versus alternatives like 'query_health_summary' or 'get_activity_details'.

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