read_realtime_vitals

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

With no annotations provided, the description carries the full burden and does disclose meaningful behavior: it activates a physical sensor, samples over a duration, and requires correct ring placement. It omits failure modes (ring not worn, sensor contact lost) and whether the call blocks for the full duration.

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 purpose is front-loaded in the first sentence and the parameter notes follow compactly with no filler. Minor formatting awkwardness from line-broken parameter lines, but nothing wasteful.

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?

An output schema exists, so return values need not be described. However, for a hardware-activating tool with zero annotations, the definition leaves gaps: the address parameter is unexplained, and there is no mention of error or readiness conditions.

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 0%, so the description must compensate. It does explain metric (naming the two valid values 'heart_rate'/'spo2') and duration_seconds (10-30s recommended), which is genuine added value, but the address parameter is undocumented in both the schema and the description.

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?

States a specific action (activating the optical PPG biosensor) and a specific resource (live Heart Rate or SpO2 measurement), which is materially different from the retrieval-oriented siblings like get_sleep_and_recovery or get_daily_activity. An agent can tell this is a live-sensor read, not a historical data fetch, without opening the schema.

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 implies the use case (live on-demand measurement) and gives the physical prerequisite that the ring be worn snugly with the sensor on the palm side. It never states when to prefer this over the historical siblings or what conditions make it fail, so usage is only implied.

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