get_daily_spo2

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

With no annotations provided, the description carries the full burden of disclosing behavior. It states the two metrics returned but does not mention pagination (despite a next_token parameter), potential latency, or any constraints beyond the ring requirement. It doesn't clarify that this is a read-only operation, though that is implied.

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 two sentences, front-loads the core purpose, and adds a crucial requirement (Gen 3+ ring) without any waste. Every word contributes.

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 that an output schema exists, the description doesn't need to explain return values. It provides the essential purpose, a hardware requirement, and the temporal context ('during sleep'). It lacks mention of pagination or date range defaults, but those are covered by parameter descriptions. Overall, it's sufficient for an agent to decide when to call it.

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?

Schema description coverage is 100%, so each parameter already has a clear description (date range and pagination). The tool description adds no additional meaning beyond the schema, so a baseline 3 is appropriate.

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 retrieves average blood oxygen saturation (SpO2 %) during sleep and the breathing disturbance index. It uses a specific verb ('Get') and names the exact resource, making it distinct from other get_daily_* 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?

The description mentions a hardware prerequisite ('Requires a Gen 3 or later ring') but gives no guidance on when to use this tool versus alternatives like get_daily_sleep or get_heart_rate. There is no mention of when not to use it or which sibling to choose instead.

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