The Eight Trigrams

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered structurally. The description adds genuinely useful details beyond that: the exact endpoint (GET /v1/iching/trigrams) and a concrete cost of 10 credits at Tier 1, which lets an agent weigh whether to spend a call on static reference data.

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?

Content is front-loaded: the single prose sentence states what is returned and its source (Shuo Gua) before the bracketed metadata lines. The group/endpoint/cost block is compact and scannable. No sentence is filler, though the attribute list is dense enough to read as a dump rather than prioritized.

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 static, zero-parameter reference lookup with an output schema available, the description supplies everything needed: content scope, data provenance, endpoint, and cost. The only meaningful gap is the absence of routing language distinguishing it from the trigram_analysis sibling, which an agent may otherwise conflate.

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?

The tool takes zero parameters, so the description bears no burden of explaining inputs and there is nothing to compensate for. Baseline for a 0-parameter tool is 4; the description neither adds nor detracts.

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 concrete resource (the eight trigrams / bagua) and enumerates exactly which attributes are returned: lines, image, attribute, family member, animal, body part, Earlier/Later Heaven numbers and directions, and five-phase element. That is far more specific than a title restatement. It stops short of differentiating itself from the similarly named sibling astroway_iching_trigram_analysis, so an agent must infer that this is the raw catalog versus an analysis.

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 phrase 'All eight trigrams' plus the '[Group: I Ching (Standalone)]' tag implies a parameterless reference lookup, which is adequate context for calling it. However, there is no explicit statement of when to choose this over astroway_iching_trigram_analysis or the other I Ching siblings, and no stated preconditions or exclusions.

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