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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered and the description is not required to restate it. What it adds beyond structured data is modest: the applying/separating nature of the results and the cost tier (100 credits, Tier 4), which is genuinely decision-relevant for an agent budgeting calls.

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?

A single front-loaded sentence states purpose and use case, followed by compact bracketed metadata lines (group, endpoint, required params, cost) that are easy to scan. Nothing is padded, though the metadata block consumes space without adding semantic content to the core sentence.

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 explanation, and annotations cover safety and idempotency; the description supplies purpose, required inputs, use domain and cost. The remaining gap is inter-sibling routing against astroway_calendar_aspects, which an agent would have to infer.

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 50%: fields and precision are documented in the schema, while year and month are only bounded integers. The description's "within a date range" plus the [Required: year, month] line confirms the two period parameters, but adds no meaning (e.g. whether month alone defaults to full-month granularity) 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 states a specific verb and resource — aspects the Moon makes within a date range — and adds the applying/separating detail, so the agent knows exactly what is computed. It does not, however, differentiate itself from the nearby astroway_calendar_aspects sibling (all bodies) or from the other Moon tools (moon_phase, moon_voc).

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?

"useful for electional and horary work" gives a use-case context, which is more than nothing, but it never says when to prefer this over astroway_calendar_aspects or the other Moon-calendar tools, and gives no exclusions or prerequisites. Usage is implied rather than directed.

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