get_daily_hydration

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

Annotations only cover readOnlyHint/openWorldHint; the description adds real behavior: the versioned endpoint path, that results are sparse ('per day that has an entry'), and that Garmin returns 400 when end - start > 30, driving the chunking strategy. That error and sparsity disclosure materially exceeds what the annotations provide.

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?

Front-loaded with the core purpose, then supporting detail; nothing is padding. The parenthetical about sweatLossInML/activityIntakeInML is useful given no output schema, though the single dense run-on sentence is harder to scan than it needs to be.

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?

With no output schema, the description supplies the return shape ({calendarDate, valueInML, goalInML}), notes omitted spec fields, and documents the failure/chunking behavior. An agent can call this and interpret the response without further sources.

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 both dates are already documented, so the baseline is 3. The description earns a bump by defining the relationship constraint between start and end (max span of 31 days, chunk beyond that), which the schema itself does not express.

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?

States a specific resource and verb ('Daily hydration in milliliters, with the goal, over a date range') plus the underlying endpoint, so the agent knows exactly what data comes back. It does not explicitly contrast with the close sibling get_hydration_data, leaving that differentiation to inference.

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?

Gives operational guidance for the 31-day window constraint ('longer ranges go in 31-day windows') and the 400 failure mode, which tells the agent how to call it correctly. It never says when to prefer this over get_hydration_data or add_hydration_data, so usage is implied rather than prescribed.

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