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), but the description adds genuinely new operational context: cost (50 credits, Tier 3), the POST endpoint, the required inputs, and a stability guarantee for the centre identifiers. The identifier-stability promise in particular is behavior the schema cannot express.

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 purpose is correctly front-loaded in the first sentence, but the second and third sentences spend most of the budget on output identifier spelling and a tangent about localised names on an unrelated /public/moon-phase endpoint, which does not help an agent invoke this tool. The bracketed metadata block is dense but useful.

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?

An output schema exists, so the description need not explain return values, yet it largely re-explains them (centre names) instead of covering the gaps: sibling routing and the semantics of the 11 undocumented optional inputs. Required parameters and cost are covered, so it is adequate but not complete for a 15-parameter tool.

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 must compensate and it does not. It documents output identifiers rather than inputs, saying nothing about ayanamsa, ayanamsaId, zodiacType, houseSystem, precision, fields, cosmogram, timezone vs timezoneOffset precedence, or name/city defaults.

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 full Human Design BodyGraph chart') and then enumerates the exact outputs: type, strategy, authority, profile, definition, incarnation cross, centers, channels, gate activations. An agent can distinguish this from the focused siblings (circuitry, incarnation cross, compatibility) without opening any schema.

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 word 'full' weakly implies this is the comprehensive base chart versus the narrower hd_* siblings, but there is no explicit when-to-use statement, no named alternative, and no exclusion. With 14+ sibling tools in the same Human Design family, the agent is left to infer routing entirely on its own.

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