Apple Health

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

Annotations already declare readOnlyHint=true and idempotentHint=true, and the description's 'Report' is consistent with that safety profile. The description does add one behavioral trait beyond annotations: the output is a cross-domain aggregation rather than a per-domain detail view. It does not disclose what 'health' encompasses or whether the aggregate depends on permissions across multiple domains, but with annotations carrying the safety burden that is acceptable.

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 sentence of roughly a dozen words that front-loads the verb 'Report' and wastes no words. Every term ('aggregated', 'across', 'MCP domains') carries meaning that helps disambiguate the tool.

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, idempotent tool with an output schema present, the description is nearly complete — return values are documented by the output schema, so the description need not explain them. The main gaps are that 'health' is never defined and the set of aggregated domains is not enumerated, which an agent might need to decide between this and the *_health siblings confidently.

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 has zero parameters, so the input schema trivially covers everything and there is nothing parameter-related for the description to add. Per the rubric, 0 params earns a baseline of 4.

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 states a specific verb and resource: 'Report aggregated health across the unified Apple ecosystem MCP domains.' The word 'aggregated' plus 'across...domains' distinguishes it from the per-domain *_health siblings in the tool list (mail_health, calendar_health, reminders_health, etc.). The phrase 'unified Apple ecosystem MCP domains' is somewhat vague about which domains are covered, which prevents a 5.

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 usage context is implied rather than stated: an aggregate health overview can be inferred from 'aggregated...across domains', but the description never explicitly says when to use this instead of the per-domain *_health tools. No exclusions or alternative routing are provided, so an agent must infer that domain-specific questions belong to siblings like mail_health or system_health.

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