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

Annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is low. The description earns credit by disclosing billing behaviour the schema and annotations omit entirely: 100 credits at Tier 4, which matters for an agent deciding whether to call it.

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?

Two tight sentences followed by compact structured tags for group and cost. The purpose is front-loaded, nothing is repeated, and every element carries 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?

With an output schema present, return values need no explanation, and cost plus participant minimum are covered. The remaining gap is routing: an agent cannot tell from this text when to pick the overlay over the compatibility or penta tools.

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 67% and the schema itself already documents the tricky fields (timezone, timezoneOffset, houseSystem letters, fields, precision) in detail. The description adds only the participant-count constraint, restating minItems rather than explaining the array shape or per-person requirements.

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 ('Calculate a combined HD group overlay chart') plus its scope ('for 2 or more people') and output ('collectively defined centers and channels'). It implicitly separates itself from compatibility/penta siblings, but never names an alternative, so the differentiation is left to inference.

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?

There is no when-to-use guidance, no prerequisite, and no mention of the closely related siblings (hd_human_design_compatibility, hd_penta, hd_circuitry) that an agent must choose between. The only eligibility hint is the implicit '2 or more people' from the schema's minItems.

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