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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states the output structure (four pillars, ten gods, hidden stems, luck cycles, strength, patterns, etc.), limits its scope to calculations only, and provides guidance on communicating results (no fortune-telling, note school-of-thought differences). This goes well beyond a minimal description.

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 concise and front-loaded with the primary purpose, followed by a single sentence outlining limitations and usage guidance. Every sentence earns its place, with no redundant or irrelevant content.

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?

Given the tool's complexity (10 parameters, nested objects, no output schema), the description provides a solid overview of the output components and clearly scopes the tool's behavior. It does not detail every parameter interaction, but it covers the essential context needed for an agent to understand the tool's capabilities and constraints.

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 high (90%), so the baseline is 3. The description mentions input modes (solar/lunar/pillars) which map to the inputMode parameter, but does not add meaningful detail about individual parameters beyond what the schema already provides. No extra parameter-level semantics are introduced.

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 the tool's function with specific verbs ('compute', 'returns') and a resource ('full BaZi chart from birth datetime'). It lists the input modes (solar, lunar, pillars) and explicitly distinguishes itself from prediction tools by stating it does no predictions or readings, which addresses sibling differentiation.

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 provides clear context for when to use the tool (compute a BaZi chart) and an exclusion ('no predictions or readings'), implying when not to use it. However, it does not explicitly name alternative tools or provide detailed use-case scenarios beyond its core scope.

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