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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the read-only nature is covered. The description adds valuable behavioral context by listing exactly what each entry returns: machine id, both spellings, length, meaning, and composed reading. It also explains the structure of the 19 periods (18 months of 20 days plus Wayebʼ).

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 sentences with no filler. The main purpose is front-loaded in the first sentence, the return content is in the second, and the intended use case is in the third. Every sentence earns its place.

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?

The description is complete enough for a list tool with no required parameters, a fully documented schema, and read-only annotations. It covers the domain logic, return fields, and use case. A minor improvement would be noting that there is a companion endpoint for fetching a single Haab month by id, but this is not essential for correct invocation.

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 coverage is 100%, so all four parameters are already well documented. The description adds contextual meaning by explaining why there are nineteen periods, which corresponds to the limit parameter's maximum, but it does not add new parameter-level guidance 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 opens with a specific verb and resource: 'Retrieve all nineteen periods of the Haab', clearly identifying the exact scope of the tool. It differentiates itself from the sibling get_mesoamerican_astrology_mayan_haab_months_id by emphasizing the full list of all periods rather than a single period.

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 gives a clear intended use case: 'Built for calendar reference pages and for any app that has to label a Haab date rather than only compute it.' This tells an agent when the list is appropriate, though it does not explicitly mention alternatives like the individual month endpoint or when to prefer those.

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