withings_get_heart_ecg

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

With no annotations, the description carries the full burden. It states the operation is a fetch (read-only) and the data type (ECG waveform), which is useful. However, it does not mention response format, potential errors, or any special requirements like authentication or device capability beyond the implicit 'ECG-capable device.' It adds context but leaves gaps, so a 3 is appropriate.

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 sentences, zero fluff. The main action is front-loaded, followed by a critical condition and an exclusion. Every sentence earns its place; it is efficient and easy to scan.

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 single-parameter fetch tool, the description covers the key context: when it is applicable, what it is not for, and the parameter source. It does not describe the output format, but given the tool name and description imply a waveform, the agent can infer the return type. It is complete enough for correct invocation.

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% because the only parameter, signalid, has a clear description: 'ECG signal id returned by withings_list_heart_records.' The tool description does not add meaning beyond the schema; it merely restates that it fetches by signalid. Baseline 3 applies since the schema already documents the parameter.

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 states a specific verb ('Fetch'), a specific resource ('ECG waveform/signal'), and the key parameter ('signalid'). It also explicitly differentiates from siblings by noting it is not for continuous watch heart rate, which sets it apart from withings_get_heart_rate.

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 gives a clear precondition: 'Only useful when withings_list_heart_records returned recordings (ECG-capable device).' It also states an explicit exclusion: 'Not for continuous watch heart rate,' which implies the alternative tool. This is explicit when/when-not guidance.

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