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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is fully covered by structured data. The description's only genuinely additive behavioral fact is the cost (100 credits, Tier 4), which is useful for budget-aware planning but is metadata rather than behavioral context.

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?

Front-loaded with the purpose sentence, then a compact bracketed metadata block for group, endpoint, required params and cost. Efficient and scannable, though the endpoint and group lines add little for an agent selecting a tool.

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?

An output schema exists, so return values need no elaboration, and the description still names the four data categories the agent gets back. For a 6-parameter read tool with full annotation coverage, this is nearly complete; only the relationship to overlapping sibling tools is left unaddressed.

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 67%, with fields, precision, timezone and timezoneOffset well documented in the schema itself; only year/month lack descriptions, and the description merely repeats that they are required. No additional parameter meaning (formats, ranges, default timezone behavior) is contributed beyond what the schema already says.

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 gives a specific verb and resource ('Calculate a lunar calendar for a given month') and enumerates the four output categories, which is more than a restatement of the title. It does not, however, distinguish itself from narrow siblings such as astroway_calendar_moon_phase or astroway_calendar_moon_voc, which cover single slices of this same data.

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?

Usage is implied by the monthly scope and the enumeration of events, but there is no explicit when-to-use guidance and no routing to the cheaper single-purpose siblings (moon_phase, moon_voc, ingresses) that an agent might prefer. The 'Required: year, month' line states inputs, not usage conditions.

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