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

The annotations already indicate readOnlyHint=true and destructiveHint=false, so the safety profile is clear. The description adds valuable details about line ordering, the yin/yang mapping, and illustrative examples that explain the behavioral contract: '111111' maps to Hexagram 1 and '000000' maps to Hexagram2. It does not discuss invalid-input behavior or the exact return shape, but annotations reduce the need for 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 description is front-loaded with the principal purpose and then quickly grounds it with parameters and examples. Every sentence earns its place, with no repetitive filler or obvious redundancy relative to the schema annotations.

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?

Given its simple read-only scope, supported by readOnlyHint and a 100% schema-covered parameter set, the description bing enough to let an agent use the tool correctly. It communicates the main input format, line order, and a representative expected result, which is sufficient for this lookup-style 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?

The schema has a 100% description coverage, so param descriptions exist. The tool description adds extra but practical meaning by defining the parameter values in terms of yin/yang, stressing bottom-to-top order, and giving examples that clarify what specific inputs produce. It does not adding meaningfully to `lang` and `compact`, but the schema sufficiently covers those.

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 states a specific action ('Find'), a specific resource ('I-CHing hexagram'), and a precise input ('binary line pattern'). It also differentiates from sibling tools by framing this as a line-pattern lookup used in custom divination interfaces, while the random and cast siblings clearly serve different purposes.

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?

It explicitly states when to use the tool: 'Use this for custom divination interfaces where users input their own line configurations, or to find hexagrams matching specific trigram combinations.' It does not name the alternative sibling tools or explicitly say when not to use this tool, which keeps it at a strong 4 rather than a 5.

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