fitbit_get_heart_rate

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

Discloses caching behavior (local cache, auto-sync if stale) and the option to bypass with live=True. No annotations exist, so description fully bears the responsibility.

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?

Description is well-structured with sections for purpose, usage, args, and returns, but slightly verbose. Front-loaded with key information.

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, description explains return values (resting_hr, zones with fields like name, minutes, etc.). Covers caching, parameter details, and default behavior completely for a 3-param tool.

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?

Despite 0% schema coverage, description explains all three parameters: start_date format ('YYYY-MM-DD', 'YYYY-MM', '30d') and default, end_date format and default, and live boolean default false. Adds significant meaning beyond schema titles.

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?

Description clearly states the tool gets daily resting heart rate and heart rate zones, with specific verb 'Get' and resource 'heart rate'. Distinguishes from sibling tools (e.g., fitbit_get_activity, fitbit_get_sleep) by being heart-rate-specific.

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?

Provides clear context on when to use default caching vs. live=true for real-time data. However, does not explicitly list alternatives or when to avoid this tool.

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