Paired devices

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real value by disclosing the return payload (battery level, last sync time) and hedges with 'when available', signalling that these fields may be null or absent — useful for an agent parsing results. It stops short of noting auth requirements or what happens with no paired devices.

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?

A single front-loaded sentence: resource first, concrete examples second, return fields last. Nothing is padded and nothing an agent needs is buried.

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 parameterless read with no output schema, the description covers what the call does and roughly what it returns, while annotations carry the safety profile. A brief note on empty-result behavior or the absence of arguments would close the remaining gap.

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 takes zero parameters, which is the baseline-4 case: there is nothing for the description to disambiguate and no schema gaps to compensate for. It would earn a 5 only if it explicitly told the agent the call requires no arguments.

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 names the resource precisely (devices paired to the account) and gives concrete examples (Fitbit Air, Pixel Watch), so an agent knows exactly what comes back. The verb 'list' is only implied by 'Devices paired to...', and it does not explicitly distinguish itself from the sibling retrieval tools.

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?

Usage is implied by the content: an agent calls this when it needs the user's paired hardware. There is no explicit statement of when to prefer it over alternatives or of any prerequisite such as an authenticated account, though the sibling tools cover unrelated data domains so overlap risk is low.

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