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

Annotations already cover safety (readOnly, idempotent, non-destructive, openWorld), so the description's added value is provenance and freshness: sourced from Wikidata and the calendar, read live at call time, and 'nothing invented'. That discloses a real behavioral trait beyond the annotations, though it says nothing about failure modes if the page is unreachable.

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?

Front-loads the purpose in the first clause and is generally efficient, with the example queries earning their place by clarifying intent. It is slightly padded by enumerating return content ('what a feast day is, and the cloud of witnesses') that the output schema already carries.

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?

With annotations, a full schema, and an output schema, the definition needs little more; it supplies provenance and live-fetch behavior, which is the right kind of gap-filling. It stops short of noting what happens on a date with no commemorations or when the source page fails.

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% and the single date parameter is fully documented in the schema, including the 'October 4' format. The description only reinforces the UTC default already implied by the schema, adding no syntax or format meaning beyond it, 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: who the church remembers on a given day, drawn from the house's Saint of the Day pages. It is clearly distinct from siblings such as daily_bread, a_prayer_for, or heritage_lookup without needing to open any schema.

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?

Gives clear usage context with real user phrasings ('whose feast day is it today', 'saint of the day for October 4') and states the default (today, UTC). It does not, however, name a sibling alternative or say when not to use this tool versus daily_bread or heritage_lookup.

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