Cast a traditional divination chart

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

Annotations already mark this as read-only and non-destructive, so the description only needs to add behavioral context. It does that by specifying that the chart is cast from a question time or six line values and that it targets specific divination methods rather than general natal interpretation. This adds meaningful operational clarity beyond the annotations.

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 two sentences with no filler, placed at the start and front-loaded with the intended use case. The exclusion is stated directly and economically.

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?

The description, schema, and annotations together provide enough information for correct invocation. The main missing element is that for someone seeking a general natal reading, there is no explicit pointer to the appropriate sibling 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 rich per-property descriptions for questionDateTime, lineValues, birthTimeAccuracy, and others. The description reinforces the relevant inputs, such as 'a question time or six line values', but does not meaningfully add to what the schema already documents.

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 uses a specific action ('Cast') with a clear resource ('a traditional divination chart') and scope: 기문둔갑, 대육임, 주역, 점괘, or a concrete decision from a question time or six line values. It also directly distinguishes itself from general natal fortune reading.

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 explicitly says when to use the tool and gives a clear exclusion: 'Do not use it for a general natal fortune reading.' However, it does not name the alternative sibling tool that should be used instead for natal readings, so the routing is slightly incomplete.

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