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

Annotations already cover read-only/idempotent/non-destructive, and the description adds genuinely non-redundant behavior: no interpretation, each rule's basis and locator included, a held-out test failure reported in result.validation, plus an attribution line and permalink. The test-failure disclosure is unusually candid and materially informs the agent about output reliability.

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?

Front-loaded with the core action and scope, and every sentence carries information (source, no-interpretation boundary, validation failure, output extras). Slightly dense phrasing and the mid-paragraph test-failure note make it a touch harder to scan, but there is no 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?

With no output schema, the description does the work of explaining what comes back: the hexagram, rule bases and locators, a validation verdict, attribution and a permalink. Given the tool's complexity and 4 fully documented params, this is close to complete; only the distinction from similarly-scoped sibling tools is left implicit.

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%, so the schema already defines date, time, place and the read_as enum. The description adds only marginal meaning (that read_as selects the book's male/female/both reading), which largely restates the enum's own description, so baseline 3 is appropriate.

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?

States a specific verb and resource: computes the He Luo birth hexagram from date, time and place, citing the source text (He Luo Zhen Shu, preface 1591) and the read_as dimension, plus an explicit 'No interpretation' boundary. It is clear what it produces, though it does not explicitly contrast itself with compute_four_pillars or get_iching_hexagram_text, which an agent could plausibly confuse it with.

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 names the inputs and the read_as choice but gives no when-to-use guidance against the many astrology/divination siblings (e.g. compute_four_pillars, get_iching_hexagram_text). It notes the result carries a validation caveat but does not tell the agent when such a chart is the appropriate call versus an alternative tool.

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