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

Annotations already cover the safety profile (readOnly, openWorld, non-destructive), and the description adds genuinely new behavioral context: it costs 2 credits, and custom year queries require a paid plan. That tier gating is the kind of caveat an agent needs before invoking. It does not describe pagination or result volume, so not a 5.

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 compact sentences, front-loaded with the resource and its returned fields, followed by plan and cost caveats in parentheses. The opening redundantly repeats the tool name twice ('Liturgical Calendar: Liturgical Calendar'), which is the only wasted text.

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 an output schema present, return values need no explanation, and both optional parameters are fully covered by the schema. The description supplies the domain, the data fields, the cost, and the plan restriction, leaving little an agent would need to guess. The unaddressed free-tier behavior for 'year' is the only loose end.

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 both 'year' and 'month' are fully documented with defaults and examples, making 3 the baseline. The phrase 'paid plans add custom year queries' adds a small amount of meaning about the 'year' parameter's availability by plan tier, but the description does not clarify what happens on the free tier or whether year is silently ignored.

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 names a specific verb and resource ('retrieves Catholic liturgical calendar events') and enumerates the returned content (feast ranks, vestment colors, seasons, holy days of obligation), which clearly separates it from generic siblings like WorldHolidays or MayanCalendar. It does not explicitly name a sibling to contrast with, so it stops 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?

Usage is only implied: the agent can infer this is the tool for Catholic liturgical data, but there is no when-to-use/when-not guidance and no routing away from the many other calendar-adjacent siblings (MayanCalendar, WorldHolidays, WorkingDays). The only constraint mentioned is a plan-tier limitation, which is not usage guidance.

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