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

With no annotations, the description carries the full burden. It usefully discloses a non-obvious behavior—returning results under both year conventions and both day boundaries and showing differences rather than hiding them. However, it omits timezone assumptions, calculation range, and output structure details.

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 definition is a single dense but front-loaded sentence: the core output is stated first, then the dual-convention behavior. Every clause contributes useful information with 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?

The tool performs a domain-specific calculation with no annotations and no output schema. The description conveys the key comparative return behavior, but leaves critical gaps such as timezone handling and the shape of the returned result, which matter for correct interpretation.

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 schema already fully documents the date and hour parameters. The description mentions date+hour but adds no semantics beyond what the schema provides.

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 resource and computation: Four pillars (BaZi) for a date and hour. It does not explicitly differentiate itself from siblings like calendar or solar_terms, but the domain-specific output is unambiguous.

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 says what the tool returns but gives no explicit guidance on when to use it versus alternatives, nor any exclusions or prerequisites. Usage is only implied by the input parameters.

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