Fetch heart rate variability (HRV) data for a given date to track recovery and readiness. Include 5-minute timeseries readings if needed.
Get Heart Rate Variability (HRV) data
Args: date: Date in YYYY-MM-DD format return_timeseries: If True, include detailed 5-minute HRV readings (can be large)
| Name | Required | Description | Default |
|---|---|---|---|
| date | Yes | ||
| return_timeseries | No |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must convey side effects or output characteristics. It only notes that time series data 'can be large', but fails to disclose what the default response contains (e.g., daily summary fields) or any performance implications beyond size. The read-only nature is not explicitly stated.
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 succinct, using a brief leading phrase and two bullet points for parameters. Every sentence adds value, with no redundant or verbose content.
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?
While the tool is simple and an output schema exists (not shown here), the description lacks details about the structure of the returned data (e.g., HRV metrics like RMSSD or stress score). It also does not clarify the relationship with related trend tools, leaving minor gaps for an agent deciding whether this is the right call.
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?
Both parameters in the schema are fully explained: the date format is given as YYYY-MM-DD, and return_timeseries is described as including detailed 5-minute readings. This exceeds the simple schema by providing practical meaning and usage details.
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 function is to retrieve HRV data for a given date, with an option to include time series. However, it does not differentiate from sibling tools like get_hrv_trend or get_heart_rates, which weakens precision.
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?
There is no guidance on when to use this tool versus alternatives. The description only explains parameters and does not mention scenarios where this tool is preferred or avoided, leaving the agent to infer usage from the name alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.