feast_date

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and determinism are covered. The description adds genuine behavioral context beyond that: it computes both Julian and Gregorian dates and handles movable feasts derived from Easter, signaling non-trivial computation rather than a simple lookup. It does not, however, disclose ambiguity handling or whether both calendar results are returned.

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 sentences, both earning their place: the first front-loads the capability, the second motivates it with concrete, culturally specific examples. No filler or restatement of the name.

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?

An output schema exists, so return-value semantics need not be explained, and the core concept plus feast examples are well covered. The remaining gap is the unaddressed influence of the 'church' parameter on movable feast dates, which an agent needs to call the tool correctly for Orthodox vs Catholic contexts.

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 only 33% — only the 'feast' parameter is documented, while 'year' and 'church' are bare. The description does not compensate: it never explains that 'church' (orthodox/catholic) materially shifts movable feast dates because Easter differs between the two, nor does it clarify the year format. With the schema leaving most parameters undocumented, the description needed to fill this gap and does not.

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 resource (the date of a church feast or fast for a given year) and specifies the computational scope — Julian and Gregorian calendars plus movable feasts counted from Easter. This clearly distinguishes it from siblings like normalize_date or convert_calendar, which deal with generic calendar conversion rather than feast lookup.

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 final sentence gives strong context for when the tool applies: records and family stories often date events by feast names, with vivid examples («родился на Покров», «венчались после Петрова поста»). It clarifies the motivating scenario but names no explicit alternative or exclusion (e.g., when to prefer normalize_date), leaving comparison to inference.

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