Trigram Analysis

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful non-schema context: the credit cost (10 credits, Tier 1) and the endpoint. Its enumeration of returned structures overlaps with the existing output schema, and it says nothing about how hexagram and lines interact when both 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?

The content is front-loaded with the input modes, then lists the derived outputs, followed by clearly bracketed metadata lines. It is one long run-on sentence of ~40 words, but nearly every clause names a distinct computed artifact rather than padding.

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?

With only two optional parameters, an output schema present, and full annotations, the definition supplies what an agent needs to call it: what inputs are accepted and what analysis is produced, plus cost. The notable gap is the lack of any statement about the relationship between the two optional inputs or its overlap with the sibling trigrams 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 100%, with both the 'lines' encoding (6/7/8/9 as old yin/young yang/young yin/old yang) and 'hexagram' (King Wen number) fully documented in the schema. The description only restates the two input modes at a high level and adds no constraints — such as precedence when both are provided — beyond the schema. 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?

The description names a specific resource (a hexagram, identified by King Wen number or six lines) and enumerates exactly what is derived: both trigrams, the image, five-phase relation, nuclear trigrams/hexagram, inverse, and complement. This is far more specific than the name alone. It falls short of a 5 because it is a noun-phrase inventory rather than a clear verb+resource statement, and it does not distinguish itself from the sibling astroway_iching_trigrams.

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 only usage signal is the parenthetical '(number or lines)', which hints at the input mode but never states when to call this versus astroway_iching_trigrams, astroway_iching_reading, or astroway_iching_lookup_number. There are no prerequisites, exclusions, or selection criteria, leaving the agent to infer from sibling names alone.

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