Fitbit Weight Logs

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description is not required to repeat safety. It adds the authentication requirement ('Requires weight scope') and a disclaimer ('Not medical advice'), which are useful but minimal. The description does not contradict annotations.

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 extremely concise: one sentence for purpose followed by two necessary statements. Every sentence adds value with no redundancy or filler.

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 relatively simple tool with three parameters and an output schema (not shown), the description covers the core purpose and a key prerequisite (scope). It does not explain return values, but the presence of an output schema mitigates this. It is adequately complete for an AI 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?

The input schema already describes all three parameters with details (date format, privacy_mode enums, response_format). The description adds no additional parameter meaning. Given schema coverage is 67% and the schema is descriptive, baseline 3 is appropriate.

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 logs for a date,' specifying the verb and resource, and the tool name itself indicates the data type (weight) and time granularity (day). Among siblings like fitbit_get_sleep_day and fitbit_get_heart_day, it is uniquely identifiable. The short description is sufficient and unambiguous.

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 mentions 'Requires weight scope,' which gives a prerequisite but does not explicitly state when to use this tool versus alternatives like fitbit_daily_summary or fitbit_weekly_summary that may also include weight data. No when-not or situational guidance is provided.

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