Fitbit Daily Heart Rate

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

The description adds little beyond the annotations, which already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint. The only additional note is 'Not medical advice,' which is a disclaimer rather than behavioral insight.

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?

Two short, front-loaded sentences with no wasted words. Purpose and key requirement are stated immediately.

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 simple read-only tool with annotations and an output schema, the description is adequate but lacks guidance on usage alternatives and parameter details. It is minimally viable but could be improved.

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 description does not explain any parameters; the schema covers 67% of parameters (with enums and defaults), but the description adds no extra meaning. Baseline would be 3 for high coverage, but 67% is moderate and the description fails to compensate.

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 it retrieves daily heart-rate zones and resting heart rate, with a specific verb and resource. While it doesn't explicitly distinguish from siblings like fitbit_get_heart_intraday, the purpose is 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 provides a prerequisite ('Requires heartrate scope') but offers no guidance on when to use this tool versus alternatives (e.g., intraday) or when not to use it. No explicit usage context is given.

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