Holidays MCP

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

Annotations already declare readOnlyHint=true, so the read-only nature is known. The description adds useful behavioral context beyond that, including the return format (date, local name, English name, type) and the country coverage limitation. It does not mention error handling or constraints on the year parameter, but for a simple read tool this is reasonably transparent.

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?

The description is composed of three sentences: the first states the core purpose, the second gives usage examples, and the third provides parameter and return details. Each sentence adds value and the text is front-loaded with the main purpose. It is slightly longer than strictly necessary, but remains concise and well-structured.

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 tool with two parameters and an existing output schema, the description provides complete context: purpose, usage examples, country_code format, coverage limitation, and return fields. It also implicitly differentiates from the sibling tool by focusing on listing, so the agent can select and invoke it correctly. No significant gaps remain.

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?

The schema provides no descriptions for the two parameters, and schema coverage is 0%. The description compensates by explaining `country_code` is a 2-letter ISO code with examples (US, GB, DE, FR, JP, ...) and that only about 100 countries are covered. The `year` parameter is left as a simple integer, but its meaning is self-evident from the tool purpose. This partial compensation is helpful, though not exhaustive.

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 clearly states that the tool returns a full list of official public holidays for a country in a given year. The verb 'get' is implied by the name, but the description uses 'Full list' to specify the scope, distinguishing it from the sibling tool is_public_holiday which likely checks a single date. It also gives example queries, making the purpose unmistakable.

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 provides specific example use cases like 'what are the holidays in Germany in 2026' and 'planning around a country's holiday calendar', which clearly indicate when to use the tool. It also states a limitation (roughly 100 countries are covered), which sets expectations. However, it does not explicitly mention when not to use it or name the alternative tool for single-day checks, so it lacks explicit exclusion criteria.

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

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

Beyond the readOnlyHint annotation, the description adds that the tool returns a boolean holiday status and the holiday's name if applicable. It also clarifies that it checks exactly one date, which is useful behavioral context. No contradiction with annotations.

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?

The description is concise yet information-dense, covering purpose, usage, parameter formats, and return behavior in just a few sentences. It is front-loaded with the core function and contains no filler.

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 two-parameter, read-only tool with an output schema, the description covers all necessary aspects: what it does, when to use it, parameter semantics, and return behavior. It is fully complete without being verbose.

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?

Despite 0% schema coverage, the description explicitly defines both parameters: country_code as a 2-letter ISO code and date as YYYY-MM-DD. This fully compensates for the lack of schema descriptions, providing precise format and meaning.

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?

Clearly states the tool checks whether one specific date is a public holiday in a country and names it if so. The verb 'checks' and specific resource (single date + country) make the purpose unambiguous. It also distinguishes from sibling get_public_holidays by noting the single-day focus.

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?

Explicitly provides usage examples and says to prefer this over get_public_holidays for single-date checks. This gives clear when-to-use guidance and names the alternative, satisfying the highest bar for this dimension.

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