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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description does add one genuinely useful behavioral fact — output is raw bytes, not JSON — which tells the agent not to parse it. It says nothing about size, content type, or whether the snapshot requires special entitlements.

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?

One sentence, zero padding, and the two load-bearing facts (what is fetched, and that the payload is bytes) are front-loaded. Nothing could be trimmed without losing information.

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?

There is no output schema, so the description carries the burden of describing the return value; 'raw bytes' is a helpful start but leaves the actual format (JSON, ZIP, binary container) unknown. For a single-parameter read tool with annotations covering safety, this is adequate but leaves an agent guessing about the payload.

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% and the single parameter is fully documented in the schema as a YYYY-MM-DD UTC calendar date. The description restates the date concept without adding format, timezone, or range constraints, so baseline 3 applies.

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 verb and resource ('Downloads the Health Snapshot') plus the scoping input ('recorded on a date') and the return type ('raw bytes'). It is clearly distinguishable from neighboring get_* stats tools, though it never explicitly contrasts itself with them.

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?

No when-to-use guidance, no prerequisites (e.g. subscription/permission tier), and no mention of alternatives such as get_user_summary or get_stats for agents that want parseable daily data. The only implied context is the date parameter.

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