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

Annotations already cover read-only, idempotent, non-destructive, and closed-world behavior, so the safety profile is handled. The description adds value beyond that by disclosing what comes back (price, where payment is made, an online ordering link) and that results are restricted to labs accepting the Hera order — meaningful since no output schema exists.

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 core purpose is front-loaded in the first clause, but the opening sentence is a long run-on that re-lists all five test types, duplicating the enum and inflating length. The second sentence (usage cue) earns its place; the enumeration does not.

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 two-parameter read tool with no output schema, the description is nearly sufficient — purpose, inputs, and returned fields are all covered. Minor gaps remain: search radius/result count behavior and whether a Hera order must pre-exist are unstated.

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 coverage is 100%: both `zip` and the `test` enum are fully documented in the schema. The description restates the ZIP locality and re-enumerates the test types already spelled out in the enum, adding no syntax, defaulting, or edge-case detail beyond the schema.

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 resource ('nearest labs') with its qualifying constraint ('that accept the Hera lab order, near a US ZIP code') and names the output contents (price, where it's paid, order link). An agent can tell this is the discovery/lookup counterpart to the singular `get_lab`, though the description never names that sibling explicitly.

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?

One concrete usage cue is given: use for "where can I get a sperm test near me" questions. There is no guidance on when to prefer `get_lab` (single-lab detail) or `hera_facts`, and no exclusions or prerequisites (e.g., whether an existing Hera order is required).

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