get_metric_stats

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

With no annotations, the description fully carries the burden. It details the returned statistics, defines the thresholds field in plain English, and explains percentile meanings. However, it does not mention authorization or side effects, which are minimal for a read-only query. The description is transparent about what the tool does and returns.

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 well-structured: first sentence states purpose, then lists output, then usage guidance, then threshold explanation. Every sentence adds value, and the most critical information is front-loaded.

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, the description need not detail return values, but it does so effectively. It explains the thresholds field, suggests a sibling tool, and provides enough context for an agent to use the tool correctly. The description is complete for the tool's 2 parameters and intended use case.

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 schema coverage is 0%, so the description must explain parameters. It implicitly covers 'metric_type' via 'any health metric' but does not describe the 'days' parameter despite its default of 90. The description adds value by explaining the thresholds field and percentiles, but fails to fully compensate for the lack of parameter documentation.

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 provides 'personal baseline statistics for any health metric' and lists specific outputs (min, max, mean, etc.). It distinguishes from sibling tools like get_daily_snapshot by explicitly suggesting pairing, making the purpose unambiguous.

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 includes explicit usage guidance: 'Use to answer: Is today's reading good or bad for me personally?' and 'Pair with get_daily_snapshot to compare today's value against your baseline.' This tells the agent exactly when and how to use the tool, with no ambiguity.

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