fitbit_get_sleep

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

With no annotations provided, the description fully carries the burden. It discloses that data comes from cache by default, that live fetching forces an API call, and that the data is sparse (only watch-tracked nights, missing travel/off-wrist). It also outlines the return structure, providing complete behavioral transparency.

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 well-structured: a one-line summary followed by logically grouped paragraphs. Every sentence adds value, though it is slightly longer than necessary. The key information is front-loaded, and the bullet-style Args list aids readability.

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 the tool's complexity (caching, live mode, sparse data, serialization across multiple nights), the description covers all essential aspects: purpose, usage guidance, parameter details, data quality caveats, and return fields. An output schema exists, but the description still explains the key return fields, making it 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?

The input schema has 0% description coverage, so the description must compensate. It does so excellently by explicitly describing each parameter in the 'Args' section: start_date format and default, end_date format and default, and live meaning. This adds critical semantics beyond the schema's bare titles and types.

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 starts with a clear verb-noun pair ('Get nightly sleep data') and immediately specifies the three key aspects: duration, stages, efficiency. The sibling tools are distinctly named (fitbit_get_activity, etc.), so there is no ambiguity about what this tool retrieves.

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 clearly explains the default behavior (cache) and when to use live=True, and mentions the prerequisite fitbit_sync. It does not explicitly state when not to use this tool, but given the distinct sibling tools, the usage context is sufficiently clear.

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