health_data_types

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

Annotations already establish readOnlyHint=true, and the description consistently describes a read-only listing operation. It adds useful behavioral context beyond the annotation by stating that every readable type is returned and that Fitbit Air-produced types are flagged, which shapes expectations without contradicting the structured metadata.

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, front-loaded sentence with no filler. Every phrase adds value: the action, the scope, and the Fitbit Air classification flag.

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 zero-parameter, read-only catalog tool with an output schema present, the description is sufficient. An agent knows exactly why to call it and what result to expect, and no invocation-time details are missing.

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 has zero parameters and schema description coverage is effectively complete, so there is no parameter burden for the description to carry. Per the baseline for zero-parameter tools, a 4 is appropriate; there is nothing meaningful left undocumented.

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 uses a specific verb ('List') with a clear resource ('every readable data type') and adds a distinguishing qualifier about Fitbit Air production flags. This makes it easy to tell apart from sibling health-data tools even without inspecting their schemas.

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 description clearly implies use when an inventory of available data types is needed, and the openWorldHint annotation supports exploration. It does not explicitly name alternatives or exclusion conditions, but the sibling tools are clearly data-value tools rather than catalogs, so the intended context is unambiguous.

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