HD Compatibility

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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real context the annotations don't carry: a fixed 100-credit (Tier 4) cost and the fact that exactly two chart inputs are required. It stops short of describing response shape, but an output schema exists to cover that.

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?

One front-loaded sentence states the operation and its output channels, followed by short bracketed metadata lines for group, endpoint, required inputs and cost. Nothing is redundant or buried, though the trailing channel list reads as free-floating rather than being labeled as the return content.

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-nested-object tool with a 100% documented schema and an output schema, the description supplies the essential framing: what is compared, what channels come back, and the credit cost. The only gap is the absence of routing guidance relative to the many other compatibility 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 100% and the nested chart objects carry unusually detailed field documentation (timezone vs timezoneOffset precedence, houseSystem letter codes, lat/lon rejection rules). The description only implies that the two parameters map to the two people, adding nothing beyond the schema, so baseline 3 applies.

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?

Names a specific verb (calculate) and resource (Human Design connection chart) and enumerates the four channel types the output covers, which distinguishes it from generic compatibility tooling. It does not explicitly contrast itself with nearby siblings like astroway_relational_synastry or astroway_horoscope_compatibility, so an agent must know the HD framing already.

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?

Usage is implied by 'compatibility between two people' and by the metadata block listing chart1/chart2 as required and the 100-credit cost. There is no statement of when to prefer this over the other compatibility tools in the catalog, and no prerequisites or failure conditions are mentioned.

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