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 implies a read-only operation ('get') but does not describe return format, pagination, date range constraints, or any potential side effects. Given the ambiguity around 'lunar days', the agent cannot anticipate what the output will look like or how to interpret the results. This is a significant gap for a tool with no structured annotations.

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 a single sentence with no superfluous words, which is concise. However, it is so terse that it borders on under-specification. While every word earns its place, the description misses the opportunity to provide valuable context without becoming verbose. Appropriate length would include a hint about the return type or intended use.

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 moderate complexity (2 parameters, no output schema, no annotations), the description is incomplete. It does not explain what 'lunar days' means, what the returned data represents, or how it differs from sibling tools. The schema covers parameters fully, but the absence of any behavioral or output context leaves significant ambiguity for an agent deciding whether to invoke this tool.

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%, with both solar_year and solar_month having clear descriptions. The tool description adds no additional meaning beyond what the schema already provides, so it meets the baseline but does not elevate understanding. The phrase 'given solar month' aligns with the parameters, but it does not clarify their relationships or formats beyond the schema.

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 'Get lunar days for a given solar month' clearly states the action (get) and the resource (lunar days) with a scoping condition (solar month). It distinguishes from sibling tools like convert_date_lunar2solar and get_lunar_vegetarian_days by indicating month-level retrieval of lunar day information. However, 'lunar days' is somewhat ambiguous—whether it means a list of days in the lunar month or mappings for each solar day—so it is not perfectly clear.

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 no guidance on when to use this tool versus alternatives. It does not mention that this tool is for month-level queries while conversion tools handle specific dates, nor does it exclude cases where lunar vegetarian days might be the intended query. There is no explicit when-to-use or when-not-to-use information, leaving the agent to infer from the name alone.

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