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

Annotations already declare read-only, idempotent, non-destructive behavior, so the bar is lower. The description adds useful context about computed real phases, returned preview plus vector PDFs/SVG, and that prints are not sold or shipped, though it does not mention auth, limits, or other operational constraints.

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-loads the use case, then covers modes, outputs, and the exclusion in a compact, well-structured way. Every sentence carries useful selection or behavioral information.

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 existing output schema, annotations, and fully described parameters, the description provides enough context to choose the tool and understand its main modes and output artifacts. No critical gap remains.

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%, so the schema already documents all parameters and enums. The description echoes the three poster kinds but adds no syntax, constraints, or parameter details beyond what the schema provides.

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 (generate moon poster) and distinguishes the three supported poster kinds: single moon, pair, and yearly lunar calendar. It also names the sibling tool it is not, making selection unambiguous.

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?

Explicitly gives when to use it (printable poster, special date, couple print, yearly calendar) and when not to use it (quick phase answer should use find_moon_phase). The alternative is named directly.

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