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

No annotations are provided, so the description carries the full burden. The description conveys that the tool computes the Day Pillar automatically and returns a reading, but it lacks critical behavioral details: no mention of output format, potential limitations (e.g., date range validity), error conditions, or performance characteristics. An agent would not know what to expect in the response beyond a vague 'reading.'

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 two sentences and gets to the point quickly. The first sentence states the purpose and scope, the second gives usage guidance. It is front-loaded with the core purpose. However, one might argue the phrase 'based on Chinese metaphysics' is slightly redundant given the tool name, but it adds context without being verbose. It is overall efficient.

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 is a simple date-based reading with 4 parameters and no output schema. The description is sufficient for a basic agent to know what the tool does and when to use it. However, it lacks important details for execution: what format the output takes, whether the reading is text or structured, how the 'lang' parameter affects output, and any limitations (e.g., dates outside a valid range). Given no output schema and no annotations, a more complete description would help the agent set expectations. It is not severely incomplete but has gaps.

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%, meaning each parameter (year, month, day, lang) is described in the schema. The description adds little beyond the schema: it mentions birth year/month/day are needed but does not add additional context such as how the date is used (e.g., does it account for time zones? Does it require a specific calendar?). The baseline of 3 is appropriate since the schema covers the basics, but no extra semantic value is added.

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 uses a specific verb ('get') and resource ('Day Pillar reading') and clearly states the domains covered (personality, career, love, wealth, health). It distinguishes itself by indicating it is a light date-based reading based on Chinese metaphysics, which is specific enough to differentiate from potential sibling tools if they existed.

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 clearly states when to use the tool: 'when a user wants a light date-based reading or asks about their personality/fortune from their birth date.' It does not explicitly mention alternatives, but with no sibling tools present, this is acceptable. It gives context on the basis (birth date) and that the service computes the Day Pillar automatically, which clarifies the input expectation.

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