Lunar Calendar MCP Server

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

No annotations are provided, so the description carries the full burden. It discloses key behavioral traits: it's a prediction tool (implying read-only, non-destructive), includes 'astronomical accuracy for reliable predictions' (suggesting precision), and outputs exact dates and times. However, it lacks details on rate limits, error handling, or response format, leaving gaps for a tool with no output schema.

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 appropriately sized and front-loaded, starting with the core function and followed by supporting details. Every sentence adds value: the first defines the tool, the second specifies output, the third gives usage contexts, and the fourth adds reliability. There is no redundant or wasted text.

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 moderate complexity (2 parameters, no output schema, no annotations), the description is mostly complete. It covers purpose, usage, and behavioral aspects like accuracy, but lacks output details (e.g., format of returned phases) and error cases. With no output schema, this gap is notable but not critical, as the core functionality is well-explained.

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%, with both parameters (start_date, end_date) well-documented in the schema. The description adds minimal value beyond the schema by implying date-range filtering but does not provide additional syntax or format details. With high schema coverage, the baseline score of 3 is appropriate as the description does not significantly enhance parameter understanding.

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 clearly states the tool's purpose with specific verbs ('predicts and lists') and resources ('moon phase transitions'), detailing the exact types of phases included (new moons, first quarters, full moons, last quarters). It distinguishes from siblings like 'get_moon_phase' (likely single-phase) and 'get_moon_calendar' (likely broader calendar) by emphasizing prediction within a date range and listing all major transitions.

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 clear context for when to use this tool ('useful for planning activities around specific moon phases, scheduling lunar observations, or understanding the lunar cycle progression over time'), which helps differentiate it from siblings focused on compatibility, festivals, or single-phase checks. However, it does not explicitly state when not to use it or name specific alternatives among the siblings.

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