True solar time

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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds genuine domain behavior beyond that: the split into meridian offset and equation of time, and the concrete Kashgar/Beijing example showing discrepancies approaching three hours. It does not state precedence between timezone and timezoneOffset, though the schema covers 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?

Two sentences plus a compact metadata block; the definition is front-loaded and the concrete example earns its place by making the correction tangible. No redundancy beyond the boilerplate Group/Endpoint/Required lines, of which the credit cost is genuinely useful.

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?

An output schema exists, so return values need not be explained, and the timezone/timezoneOffset interlock is well handled inside the schema. What remains is the domain rationale, which the description supplies; only the usage context relative to bazi tooling 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 only 33%: date, time, and timezoneOffset carry no schema descriptions, and longitude's range is documented without meaning. The description only clarifies that longitude is the birth longitude; it adds nothing about date/time formats or the sign convention of timezoneOffset, so it fails to compensate for the coverage gap.

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 the specific computed quantity (clock corrected to the sun over the birth longitude, split into meridian term and equation of time) and even cites its downstream effect on the hour pillar, so an agent knows exactly what it produces. It is phrased descriptively rather than as an imperative and never contrasts itself with nearby tools such as the bazi hour pillar or solar terms endpoints.

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?

There is no explicit when-to-use statement, no prerequisites, and no named alternative. The reference to 'which moves the hour pillar' hints that this precedes a bazi hour-pillar calculation, but the agent must infer that, and nothing tells it when true solar time correction can be skipped.

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