get_lunar_phase

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

With no annotations, the description discloses data source (NASA JPL DE421 via Skyfield), default behavior (current date if not specified), and the type of output (illumination percentage and interpretation). This is good transparency for a read-only tool.

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 concise (7 short sentences) with a clear structure: purpose, phase interpretations in bullet format, data source, and parameter documentation. Every sentence adds value, no redundancy.

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 presence of an output schema (not shown), the description appropriately focuses on inputs and purpose. It covers parameter, data source, and phase meanings, but could add brief mention of error handling or return format expectations.

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 schema provides no description for the date parameter (0% coverage), but the description compensates by specifying it is optional, ISO 8601 format, and defaults to current date/time. This adds necessary meaning 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 explicitly states it returns 'lunar phase with illumination percentage and a software development interpretation', with specific phase meanings. This clearly distinguishes it from sibling tools like get_planetary_status or get_cosmic_risk_score.

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?

The description provides contextual usage guidance through phase interpretations (e.g., 'New Moon → poor time for deployments'), implying when to use. However, it lacks explicit when-not-to-use or direct comparison with sibling tools.

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