Get Moon Phase

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true. Description adds value by specifying the exact output fields, that datetime defaults to now, and the nature of computation. No contradictions, and provides clear context beyond 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?

Two concise sentences plus an example. No redundant information. Front-loaded with key output details. Every sentence adds value.

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 simplicity, full schema coverage, annotations, and presence of output schema, the description is complete. It covers return values, parameter behavior, and provides an example usage.

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 100%, so baseline is 3. Description adds clarity by explaining that 'datetime' defaults to now and that 'timezone' should be omitted if datetime carries UTC offset. This practical guidance goes beyond the schema descriptions.

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?

Description clearly states verb 'get' and resource 'moon phase', lists specific return fields (phase angle, common name, illuminated fraction, moon sign, next four quarter events), and provides an example. Distinguishes from sibling tools which are other astrological computations.

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?

Description implies usage for moon phase queries via example, but does not explicitly state when to use versus alternatives among siblings (e.g., get_planet_position, find_eclipses). No exclusions or when-not-to-use guidance.

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