Heart / ECG (Withings)

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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds the dual-mode behavior (list by date range or fetch by signalId), which is not captured by annotations alone. It does not mention edge cases like conflicting parameters, but the core behavior is transparent.

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 a single, concise sentence (14 words) that front-loads the tool's purpose and key usage modes. No wasted words; every phrase adds value.

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 simple read tool with strong annotations and no output schema, the description adequately conveys the return context ('List' implies an array, 'fetch' implies a single ECG signal). It is missing clarification on parameter conflicts or required combinations, but overall it is reasonably complete for the tool's complexity.

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 carries the burden. It maps startDate/endDate to the date-range list mode and signalId to the individual ECG fetch mode, adding meaning beyond the raw schema. It lacks details on parameter combinations (e.g., both date range and signalId) but effectively explains primary usage.

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 uses specific verbs ('List' and 'fetch') and names the resource ('heart/ECG recordings'), clearly distinguishing it from sibling tools like withings_get_activity and withings_get_sleep. It also identifies two distinct modes, making the tool's capabilities unambiguous.

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 clear context for when to use the tool ('for a date range' vs 'by signalId'), but it does not explicitly mention alternatives or exclusions relative to sibling tools. Since the resource type is clearly heart/ECG, usage is implied but not compared against other getter tools.

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