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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely new operational context by disclosing the billing cost ('Cost: 1 credit') and the shape of the returned calendar components, but says nothing about supported date ranges, precision, or failure behavior for out-of-range dates.

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?

Three short sentences, front-loaded with the core transformation and followed by the return components and cost. The only waste is the redundant repetition of the tool name ('Mayan Calendar: Mayan Calendar converts...'), which duplicates the title field.

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 one-parameter date converter with an output schema and read-only annotations, the description covers purpose, output components, and cost, which is enough to call it correctly. The main omission is guidance on valid date range or whether historical/proleptic Gregorian dates are handled.

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?

With a single parameter at 100% schema description coverage, the schema already documents the YYYY-MM-DD format and supplies an example. The description adds no additional meaning about the date argument, so the baseline 3 applies.

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?

States a specific verb and resource ('converts Gregorian dates to the ancient Mayan calendar system') and enumerates the three output calendars (Long Count, Tzolkin, Haab), so the transformation is unambiguous. It does not name any sibling such as JulianDayCalculator or ChineseZodiac to draw an explicit boundary, so it falls short of a 5.

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 never states when to reach for this tool versus alternatives, nor any precondition or exclusion. A reader must infer usage entirely from the one-line purpose statement.

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