Lunar Calendar MCP Server

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

With no annotations provided, the description carries full burden and does well by disclosing key behavioral traits: it's a calculation tool (not a simple lookup), returns comprehensive data (phase name, illumination, age, times, position), and emphasizes precision and location-awareness. It doesn't mention error handling or performance characteristics, but covers core functionality adequately.

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 efficiently structured in two sentences: the first states the core purpose and key return values, the second adds important context about location-aware calculations. Every phrase adds value with zero redundant information, making it easy to parse.

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?

For a calculation tool with 2 parameters, 100% schema coverage, and no output schema, the description provides strong context about what data is returned and the precision of calculations. It could improve by mentioning error cases (e.g., invalid dates) or output format, but is largely complete for its complexity level.

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 both parameters thoroughly. The description adds marginal value by reinforcing that calculations are 'for a specific date and location' and 'location-aware', but doesn't provide additional syntax, format details, or constraints beyond what the schema specifies.

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 ('calculates', 'returns') and resources ('moon phase information'), distinguishing it from siblings like 'predict_moon_phases' or 'get_moon_calendar' by focusing on precise astronomical calculations for a specific date/location rather than predictions or calendar views.

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 implies usage context by mentioning 'specific date and location' and 'location-aware calculations', but does not explicitly state when to use this tool versus alternatives like 'predict_moon_phases' or 'get_moon_calendar'. No guidance on exclusions or prerequisites is provided.

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