fitbit_get_sleep

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

With no annotations, the description carries full burden for behavioral disclosure. It reveals that data comes from local cache by default, that live=True fetches from the API, that fitbit_sync must be run first, and that data is sparse (missing travel/off-wrist/manual logs). This is rich, honest context beyond the basic function.

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 appropriately sized for the tool's complexity, with a clear 'Args:' section. It is front-loaded with the main purpose and usage caveats. A few sentences could be tightened, but every sentence adds value.

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?

The description covers the tool's behavior (cache vs. live, sync dependency), input formats, data sparsity, and return fields (total_minutes, efficiency, start/end times, stage breakdown). With an output schema present, it doesn't need to detail return types further, making it complete for a 3-parameter tool with no annotations.

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 description coverage is 0%, so the description must fully explain parameters. It does: start_date formats ('YYYY-MM-DD', 'YYYY-MM', or '30d') and default (last 30 days), end_date format and default (today), live boolean default false. It also explains the return structure, compensating entirely for the missing schema descriptions.

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 'Get nightly sleep data (duration, stages, efficiency)', using a specific verb and resource. It differentiates from sibling Fitbit tools by focusing on sleep and describing cache vs. live data. The tool name and description align perfectly.

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 explicit guidance: 'Run fitbit_sync first to populate the cache' and 'Use live=True to fetch from Fitbit API.' It also warns about data sparsity for nights without watch-tracked sleep. However, it doesn't explicitly state when not to use this tool versus other sleep-related siblings, though the context is clear.

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