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

The readOnlyHint annotation already declares the safety profile, and 'Read-only' in the description largely repeats it. The description does add useful context that the identity comes from the API key and that this call doubles as an auth check, but it says nothing about behavior on an invalid key or what the account payload contains. With annotations carrying the safety burden, 3 is appropriate.

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 with zero filler, and the identity of the resource is front-loaded ahead of the usage hint. Nothing could be cut without losing content.

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 no-parameter, read-only tool with no output schema, the description covers what it returns conceptually (the authenticated account) and how to use it. It does not enumerate the fields the account object carries, which is the only remaining gap, and that omission is minor given the tool's simplicity.

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 tool takes zero parameters, so per the rubric the baseline is 4. There is nothing to document beyond the implicit fact that the account is derived from the API key, which the description does state, so no compensation is required.

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 names a specific verb and resource ('Fetch the authenticated Healthie account') and pins down identity with '(the provider/user that owns the API key)'. That parenthetical is what separates it from the sibling healthie_get_user, which retrieves an arbitrary user rather than the caller. An agent can choose between them without opening either 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 gives an explicit when-to-use context: 'Good first call to verify auth.' That is a clear situational cue for an agent starting a session. It stops short of an explicit exclusion ('use healthie_get_user when you need another user's record'), so it lands at 4 rather than 5.

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