fitbit_get_weight

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

With no annotations provided, the description carries full burden. It discloses that data comes from a local cache by default, requires a sync first, is sparse (only days with weigh-ins), and returns one entry per weigh-in with specific fields. This is valuable behavioral context beyond the schema.

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 with a brief introduction, a note on cache and sparse data, and a clear Args list. Every sentence adds value—no redundancy or irrelevant details. The format is easy to scan and understand.

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 is complete for the tool's complexity: it covers parameters, return format, cache behavior, and prerequisites. Some minor missing details like error handling or timezone considerations, but these are not essential for selection and invocation. The output schema also lessens the need to describe return values.

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%, but the description's Args section fully explains each parameter: start_date format and default, end_date format and default, and live flag meaning. This compensates entirely for the schema's lack of descriptions, adding critical format details like 'YYYY-MM-DD', 'YYYY-MM', or '30d'.

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 weight log entries (weight, BMI, body fat percentage)', specifying the verb, resource, and scope. It distinguishes from sibling tools like fitbit_get_food_log and fitbit_get_activity by focusing on weight-specific data, and the mention of cache vs. live modes further clarifies its role.

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 instead of cache.' It also clarifies default behavior (cache) and data sparsity. It does not explicitly contrast with alternative tools, but the prerequisites and mode selection are clear.

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