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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description earns credit for adding operational facts beyond them: the 50-credit Tier 3 cost, the POST endpoint, and the deterministic line/profile rule that decides right-angle vs juxtaposition vs left-angle. It does not describe failure modes or what happens when conflicting inputs (birth data plus gates) are supplied.

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 front-load the outcome, the input modes, and the returned components, followed by a compact bracketed metadata block for group, endpoint, required fields, and cost. Nothing is padded or repeated.

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 tool with 15 parameters and low schema description coverage, this is thin, but the presence of an output schema removes the obligation to explain return values, and the metadata block supplies cost/endpoint/required fields. The gate-number input path mentioned in prose but absent from the schema is a real completeness gap.

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 only 33% across 15 parameters, so the description would need to carry weight, and it does not — it names the four required fields and nothing else. Worse, it references inputs ('gate numbers', 'personalitySunLine', 'designSunLine') that do not appear anywhere in the input schema, which risks confusing an agent about how to trigger the alternate mode.

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 first sentence gives a specific verb and resource ('Return the Incarnation Cross') and names the two input modes (birth data or gate numbers), plus what the result contains (name, type, theme). It does not explicitly differentiate itself from nearby siblings such as astroway_hd_human_design or astroway_hd_hologenetic, which presumably also derive from birth data, but the resource itself is unambiguous.

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?

It implies two usage paths ('from birth data (or directly from gate numbers)'), which is a useful fork, but never states when to prefer this tool over the other Human Design endpoints or any exclusions/preconditions. Usage has to be inferred from the domain.

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