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

Beyond the readOnlyHint and idempotentHint annotations, the description discloses determinism, the input-dependent behavior, the absence of divination, and the attribution/license requirement. This adds meaningful context about what the tool does and does not do.

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 three tightly written sentences. It front-loads the core purpose and behavior, then adds the licensing note. Every sentence earns its place with no redundancy or filler.

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 the rich schema, output schema, and annotations, the description provides all necessary context: purpose, behavior under different inputs, determinism, and licensing. Nothing essential is missing for an agent to select and invoke the tool correctly.

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 coverage is 100%, so the baseline is 3. The description adds value by explaining the effect of changing_lines: empty values return primary only, while non-empty values include the resulting hexagram and transition. It also reinforces the range and ordering constraints already present in the schema.

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 clearly states a specific function: 'Deterministic reading context for a primary hexagram (1-64) and 0-6 ascending changing lines.' It distinguishes itself from sibling tools by emphasizing the changing-lines behavior and clarifying that no divination is performed.

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 provides clear behavioral guidance on when to use the tool: empty changing_lines returns the primary hexagram only; changing lines add resulting hexagram and transition. It implies the tool is for reading context rather than divination, though it does not explicitly name alternative sibling tools.

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