get_daily_health_facts

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

With no annotations, the description carries full burden. It discloses a key non-obvious behavior: 'Activity values intentionally refer to the previous calendar day.' It also clarifies the scope (one recovery date) and the default (today). No mention of side effects, but as a read operation this is sufficient.

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, using two short paragraphs. The first sentence front-loads the purpose. The second paragraph adds necessary detail. No extraneous information, though the first sentence could be slightly tighter.

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 simple single-parameter read tool with an output schema, the description covers the essential context: purpose, parameter format, and a behavioral quirk (activity lag). It does not mention error handling or missing data, but overall it is complete enough for an agent to use correctly.

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 0% but there is only one parameter. The description adds significant meaning: date format (YYYY-MM-DD), optionality, and default behavior (today). This goes well beyond the raw schema which only provides type constraints.

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 'Return calculated health facts and 7/28-day baselines for one recovery date' with a specific verb and resource. It also details the data elements (sleep, resting heart rate, HRV). However, it does not explicitly differentiate from sibling tools like get_daily_health_pulse, though the unique mention of baselines and activity lag provides some distinction.

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 provides syntactic guidance on using the date parameter ('Use YYYY-MM-DD or omit the date for today'), but no guidance on when to use this tool versus sibling tools (e.g., get_daily_health_pulse, get_health_history). The agent receives no context on alternative selection.

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