get_hrv_history

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

With no annotations, the description must carry the behavioral burden. It does disclose the array ordering ('newest-first') and the data composition, which is real added behavior, but says nothing about data freshness, behavior when fewer than `days` of history exist, or that the call is a safe read.

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?

Three short sentences, front-loaded with what is returned before the sibling comparison. The quoted 'how am I today' phrase is slight color but earns its place by making the routing rule concrete.

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 explained, and one optional parameter plus the sibling routing are both covered. Minor gaps remain around how the baseline is computed and what happens with insufficient history.

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 coverage is 100% and the single `days` parameter is fully documented with default, min, and max in the schema. The description only gestures at range ('longer range'); it adds no interpretation beyond the schema, so the baseline 3 applies.

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 first line names the resource precisely (daily HRV) and enumerates what it contains: last-night value, weekly average, and a baseline. It also explicitly distinguishes itself from the sibling get_recovery by contrast, so an agent can pick between them without opening a 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?

It states exactly when get_recovery suffices ('how am I today') and when this tool is needed (trend questions), naming the alternative and the condition that selects it. The 'same data over a longer range' framing removes any ambiguity about overlap.

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