garmin_add_hydration

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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the safety profile is covered, but the description adds nothing beyond that. It omits the notable behavioral quirk that a negative value removes an entry (a removal-like effect despite destructiveHint=false) and says nothing about auth or how repeated logs accumulate.

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?

A single front-loaded sentence with zero filler, so it is efficiently structured. It is arguably over-terse for a mutation tool whose negative-value behavior deserves a clause, which keeps it off a 5.

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 2-parameter logging tool with fully documented schema and no output schema, the description is minimally sufficient to call correctly. It still leaves gaps around what success returns and how the removal semantics interact with a non-destructive annotation.

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 100%, with `ml` documented as 'Millilitres; negative removes' and `when` listing accepted formats, so the baseline is 3. The description contributes no additional parameter meaning, such as sensible ranges, defaults, or whether `when` defaults to server-now.

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?

"Log water intake" gives a specific verb and resource, and "Garmin Connect's hydration tracker" scopes where the write goes, which separates it from siblings like garmin_log_food or garmin_add_weigh_in. It stops short of naming an alternative explicitly, so an agent must infer the boundary from the resource name alone.

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 when-to-use, when-not-to-use, or alternative routing guidance; the agent cannot tell from the description whether this differs from garmin_log_food or garmin_set_nutrition_goals. The only usable usage signal is the implied 'add a hydration entry', which the name already conveys.

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