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

Annotations already establish this as read-only and non-destructive. The description adds useful behavioral context: the fixed true-direction alignment, the exact field content returned, and the guarantee that trigram details match the I-Ching trigram endpoints field for field. It does not describe pagination or response framing, but the schema partially covers 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?

The core content is front-loaded and the following sentences provide orientation semantics, data-source consistency, and use cases. It is economical and mostly earns its sentences, though the 'Built for...' sentence is slightly more expansive than strictly necessary.

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 read-only list endpoint with no required parameters, the description plus fully documented schema are sufficient for correct invocation. The field list and compact-shape documentation mitigate the absence of an explicit return-shape sentence, leaving only a minor 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 100%, and each parameter (lang, limit, offset, compact) already carries a clear description in the schema. The tool description contributes no additional parameter-level semantics, so this stays at the baseline for high schema coverage.

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 precisely identifies the resource: the nine palaces of the compass Bagua map, including the eight trigram sectors and the centre, with life areas, five phases, colours, and trigrams. It is clear but does not use an explicit action verb like 'returns' or 'lists', and it does not directly name sibling endpoints; the title supplies the List action.

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 description gives concrete intended uses ('floor plan overlays, room-by-room guides') and clarifies the compass-based orientation model (career is always North, wealth always Southeast). This implicitly distinguishes it from entrance-facing approaches, but it stops short of naming a specific alternative tool or saying when not to use this one.

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