fitbit_get_devices

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

With no annotations provided, the description carries the full behavioral burden. It discloses the live-only (no caching) behavior, reflects current device state, and specifies the return structure (one entry per device with listed fields). This goes beyond a simple statement and adds useful operational context, though it doesn't cover auth or error conditions.

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 three well-structured sentences: first states the main function, second adds behavioral context and use cases, third details the output fields. Every sentence adds value with no repetition or filler, making it appropriately sized and front-loaded.

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?

This is a simple no-parameter tool with an output schema, and the description covers all necessary aspects: purpose, behavior, use cases, and return format. It effectively differentiates from the many sibling tools and provides enough context for an agent to select and invoke it 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 tool has zero parameters, so the baseline is 4. The description correctly implies that no filtering is possible (lists all paired devices), which aligns with the empty input schema. No parameter details are missing because there are none.

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 the tool lists paired Fitbit devices with battery level and last sync time, using a specific verb and resource. This distinguishes it from sibling tools like fitbit_get_activity or fitbit_get_sleep, which target different data domains.

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 use cases (monitoring tracker health, knowing which device produced data, spotting sync gaps) and notes the live-only behavior, implying when to use this tool. However, it doesn't name alternative tools or state when not to use it, leaving some room for interpretation.

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