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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. Beyond that, the description adds the computational scope (which star systems and palace attributes are produced), which is genuinely useful, but says nothing about output format, precision limits, or how inputs like birth_time versus hour_index affect the result.

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?

A single front-loaded sentence that begins with the verb and resource before the detail list. The enumeration of 12 palaces is long but each item conveys scope, so little is wasted; splitting the domain terms from the behavioral notes would improve scanability.

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?

For a simple read-only chart generator with no output schema, the description conveys the result content but omits the response shape and any routing versus tuvi_horoscope. It is adequate but leaves the agent guessing on the most likely confusion point among siblings.

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%, including the precedence rule for birth_time over hour_index and the gender encoding, so the schema carries parameter meaning fully. The description adds no parameter-level detail beyond the schema, making the baseline 3 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 ("Lập lá số", cast a chart) and resource (Tử Vi chart) and enumerates exactly what the output contains: 12 palaces, star brightness levels, auxiliary stars, Tuần/Triệt, Thân cư and Mệnh cư. It never names a sibling, so the agent cannot tell from this text alone how it differs from tuvi_horoscope or bazi_chart, which keeps it below a 5.

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 guidance on when to use this tool versus the obvious sibling tuvi_horoscope, and no prerequisites such as whether the birth date must be solar (implied only through the schema). The agent must infer usage entirely from the name and purpose sentence.

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