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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds that results are ordered from Cipactli to Xochitl and complete in one call, but does not disclose pagination, language fallback, or compact-response behavior; those live in the schema, so a 3 is appropriate.

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?

Two efficient sentences with no filler: the first states what is retrieved and returned, the second states intended use cases. Key scope information is front-loaded.

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 simple read-only list endpoint with 100% schema coverage and no required parameters, the description covers the domain, output fields, ordering, and use cases. It does not describe the exact JSON envelope, but with no output schema that is a minor gap; the schema and annotations cover the rest.

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% and each parameter (lang, limit, offset, compact) already carries a detailed description with defaults and ranges. The tool description adds no parameter-specific meaning, 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?

The description opens with a specific action and resource: 'Retrieve all twenty tonalpohualli day signs in sequence order from Cipactli to Xochitl.' It also states the output fields and explicitly frames this as 'the whole set in one call,' which distinguishes it from the singular get_..._day_signs_id and Mayan siblings.

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?

It gives clear use cases: 'Built for Aztec sign pickers, Mexica calendar reference pages and any app that needs the whole set in one call.' However, it does not explicitly say when not to use it or name the single-sign alternative, so it falls short of a full 5.

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