fitbit_get_hrv

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

No annotations provided, so description carries full burden. Discloses caching behavior, conditions for data availability (on-wrist sleep), premium requirement, and even interprets RMSSD values. No side effects or alterations – fully transparent.

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?

Well-structured with leading summary then bullet details. Every sentence adds value. Could be slightly more compact but remains efficient.

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 no annotations and low schema coverage, description fully equips an agent: purpose, parameters, behavior, return values with interpretation, prerequisites, and constraints. Complete for correct invocation.

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 has 0% description coverage, but description extensively covers each parameter: date formats, defaults, meaning of live flag. It adds full semantic context beyond the JSON schema.

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?

Specific verb+resource: 'Get nightly HRV (heart rate variability) data'. Clearly distinguishes from siblings like fitbit_get_activity, fitbit_get_sleep, etc.

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?

States default cache behavior, live flag for API fetch, prerequisite sync, and constraints (sparse data, premium requirement). Could mention when not to use but context is clear.

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