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

The annotations already declare the full safety profile (readOnly, idempotent, non-destructive, closed-world), so the description need only add new behavior. It does add one genuinely useful trait not in the annotations: the cost of 5 credits (Tier ½), which matters for an agent deciding whether to spend. Beyond that it says nothing about what the response contains or any constraints.

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?

Three short lines with the topical keywords front-loaded and the group/cost metadata clearly bracketed, so there is no filler or redundancy. It is efficient, though arguably terse to the point of underspecification, which is a completeness issue rather than a conciseness one.

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 return values need not be described, and annotations cover the safety profile. However, for a parameterized chart tool the definition leaves the agent without a clear statement of what is produced or how it differs from the sibling Zi Wei palace tools, making it only minimally sufficient.

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?

Six parameters with schema description coverage at 67% and the description adds zero parameter information. The required 'date' parameter has only a pattern, and nothing in the description clarifies the date/time/timezone semantics or the compact-mode fields/precision options. With a mid-range coverage gap, the description should compensate but does not.

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 description names the life themes the Siblings Palace covers ('Brothers, sisters, peer relationships') but supplies no verb and never states that it returns a Zi Wei Dou Shu palace analysis, so the function is only implied. It is largely a restatement of the title 'Siblings Palace (Xiongdi)' with the addition of 'peer relationships', and it does not distinguish itself from nearby Zi Wei palace tools or from astroway_family_sibling_dynamics.

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 prerequisites (e.g. a birth date/time is required), and no mention of alternatives such as astroway_ziwei_twelve_palaces or astroway_family_sibling_dynamics. The only contextual cues are the group tag and credit cost, which are billing/metadata rather than usage direction.

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