fitbit_get_activity

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

With no annotations, the description fully carries the behavioral transparency burden. It discloses the default cache-backed behavior, the live=True fallback, rate-limit implications, and even the active_minutes aggregation formula (very_active + fairly_active). This is rich, useful context.

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 summary, a clear note, and parameter breakdown. Each sentence contributes essential information—no redundancy or filler. It is appropriately sized for a data-fetching tool with non-obvious behaviors.

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 output schema exists, return-value details aren't strictly required, but the description still explains the output shape ('one entry per day') and key metrics. It also covers prerequisites and rate limits, making it complete for a wide range of user intents.

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 schema provides zero descriptions, but the description's 'Args' section compensates thoroughly. It explains start_date acceptable formats ('YYYY-MM-DD', 'YYYY-MM', '30d'), default behavior, end_date default, and the live boolean semantics—far exceeding the schema alone.

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 opens with a specific verb-resource combination: 'Get daily activity summaries' and enumerates key data fields (steps, calories, active minutes, distance). This clearly distinguishes it from sibling tools like fitbit_get_sleep or fitbit_get_food_log.

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 clear usage context: it explains the cache-vs-live distinction, instructs users to run fitbit_sync first, and warns about API rate limits. It doesn't explicitly mention when to choose an alternative sibling, but the guidance is practical and actionable.

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