Wikipedia On This Day

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

The annotations already provide readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the non-mutating, safe, repeatable nature of the call. The description adds a meaningful behavioral caveat: the year in the date input is ignored, and only month/day are used. It also discloses licensing (CC BY-SA 4.0), which is beyond what annotations provide. It does not discuss pagination or result limits, but the output schema presumably covers the response shape.

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 three sentences and front-loads the core purpose and primary constraint. The use cases and licensing add practical context without excess. Minor redundancy: the parameter schema already states the 'year is ignored' behavior and the default-to-today behavior, so the description repeats some schema content, but it is concise overall.

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?

This is a simple one-parameter read-only tool with an output schema, so the description does not need to document return fields. The essential selection and invocation context — purpose, data scope, licensing, and the year-ignored caveat — is present. The only gap is a lack of explicit guidance on result count/limits or 'when not to use', but these are minor given the tool's simplicity.

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 the single parameter `date` is already well documented in the schema, including format, defaulting behavior, and the fact that the year is ignored. The tool description reiterates the month/day behavior, which is consistent but not additive. This matches the baseline of 3 for high schema coverage.

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 states a specific verb and resource: 'Retrieve historical events that occurred on a given month/day across all years', and it specifies the return payload (event text, year, up to 3 related article links). It is clearly distinguishable from sibling tools like wikipedia.feed.featured, wikipedia.article.summary, and wikimedia-rest.feed.on_this_day, which appear to be different endpoints or content types.

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 identifies concrete use cases: 'history timelines, date-based trivia, and anniversary lookups'. This gives an agent clear context for when to invoke it. It does not explicitly name alternative tools to exclude or provide a when-not-to-use clause, but the use cases plus the tool's scope make the selection relatively clear.

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