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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds behavioral context by saying the facts are 'in its own words', indicating the answers use Hera's own phrasing rather than an independent summary. It also reveals the breadth of content without contradicting any annotation.

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 that names the resource before listing all supported topics. Every listed item corresponds to a valid enum value, so there is no filler. It is long but appropriately so, given the tool covers many distinct fact categories.

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 simple one-parameter, read-only facts tool, the description covers the full range of available topics and the nature of the content. It does not describe the exact return format, but 'facts' sufficiently implies textual answers. The lack of an output schema is not a major gap here because the tool's behavior is straightforward.

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 sole parameter `topic` is fully enumerated in the schema, and the description mostly repeats those enum values in natural language. It does add readable labels like 'at-home collection' and 'post-vasectomy checks', but it does not define the topics or explain how to map user intent to each enum value. Since schema description coverage is 0%, the description provides only marginal semantic value beyond the enum.

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 clearly identifies the resource as Hera Fertility facts and enumerates the full topic scope, so an agent can tell what the tool returns. It does not use an explicit verb like 'returns' or 'explains', but the content is unambiguous. It is also distinct from the sibling lab-lookup tools by nature.

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 implies when to use the tool: whenever a user asks about Hera's services, pricing, process, results, privacy, or related topics. It does not explicitly state when not to use it or compare against find_labs/get_lab, but the topic list provides clear context for selecting it.

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