Get Hydration

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

Annotations already declare readOnlyHint true, covering the primary behavioral trait (read-only). The description adds no further behavioral details (e.g., behavior when no data exists, response format). Since the annotation covers the safety aspect, this is acceptable, but the description doesn't enrich beyond that.

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, clear sentence that immediately states the tool's purpose. It is front-loaded and contains no redundant or filler content. Every word contributes to understanding.

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 one-parameter retrieval tool with read-only annotations, the description is mostly sufficient. However, since there is no output schema, it could have briefly mentioned what data is returned (e.g., units, structure). But given the simplicity, missing this is not critical.

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?

The input schema provides a full description of the 'date' parameter (format, default), achieving 100% coverage. The tool description offers no additional parameter semantics beyond what the schema already states. With high schema coverage, the baseline of 3 is appropriate.

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 identifies the action (get) and specific resource (daily hydration/water intake data) with a scope (for a specific date). This distinguishes it from sibling tools like add_hydration_data (write) and other data getters (e.g., get_steps, get_heart_rate), making the purpose 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 usage context is clear: use this tool when you need hydration data for a particular date. The description implies this without explicitly mentioning alternatives or when-not-to-use. Since it's a specialized getter and no alternative for reading hydration data exists among siblings, this is adequate, though it could have noted that it's read-only (already covered by annotation).

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