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 structurally. The description's genuine addition is the cost disclosure ('100 credits, Tier 4') and the endpoint, which help an agent reason about budget. It adds nothing about output granularity or volume of matches, so a 3 is warranted.

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 core sentence is front-loaded and the bracketed metadata block is compact and scannable. Every line earns its place, with no redundancy or filler to trim.

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 shape need not be described, and annotations carry the safety profile. The description supplies endpoint, required params, and cost, which is sufficient for an agent to invoke it correctly. Only the distinction from sibling cycle tools is 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 coverage is only 33% (fields and precision are documented there, the four required ids/dates are not). The description compensates partly by naming the four required parameters and framing planet1Id/planet2Id as a conjunction pair, but adds no value for the undocumented precision/fields semantics, which the schema handles itself.

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?

States a specific verb and resource ('Find all conjunctions between two planets within a date range') and adds the domain outcome ('defining the start of a new synodic cycle'). This is clear and self-contained, but it does not differentiate itself from close siblings like astroway_calendar_cyclic_index or astroway_calendar_planetary_phases, so the agent can't tell them apart from the text alone.

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?

There is no when-to-use guidance and no named alternative. The metadata lists required parameters and a cost tier, but never says when this tool is preferred over the related cyclic_index or aspects calendar tools. Usage must be inferred entirely from the purpose sentence.

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