calculate_moon_phase

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

No annotations are provided, and the description gives no behavioral details such as calculation method, handling of timezone, what output to expect, or any edge conditions. This leaves the agent fully in the dark about the tool's behavior.

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 description is a single sentence with no redundancy or wasted words, making it very concise. However, it lacks any structural elements (e.g., separate sections) but that is acceptable for a tool of this simplicity.

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?

There is no output schema, so the description would need to explain what the tool returns, but it does not. While the tool is simple with only two parameters, the missing return-value information and lack of any usage context make it incomplete.

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?

The input schema fully documents both parameters (date and timezone) with helpful descriptions and defaults, so the baseline score of 3 applies. The description adds no additional parameter meaning beyond the general notion of a date.

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 uses the specific verb 'calculate' with resource 'moon phase' and scope 'specific date', clearly stating the tool's purpose and distinguishing it from sibling time/date tools.

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?

No explicit guidance on when to use this tool versus alternatives. The description merely states what it does; it does not mention exclusions or present alternative tools for comparison.

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