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

Annotations already declare readOnly, idempotent, non-destructive behavior. The description adds value by specifying the exact content components returned (featured article, most-read, picture of the day, on-this-day events), giving a concrete sense of the tool's output without contradicting 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 two sentences with no filler. The first sentence defines the tool's purpose and scope, and the second offers concrete use cases. It is front-loaded and every word earns its place.

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?

The tool is read-only and has a strong output schema, so the description need not explain return values. It adequately conveys purpose and usage, but the lack of parameter explanations for lang/project means the description is not fully self-sufficient for a 5-parameter tool.

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 0%, and the description only references the date components ('specific date') without explaining the purpose of lang or project. The parameter names and examples provide some hints, but the description does not compensate for the lack of schema descriptions, leaving the agent to infer the semantics of language and project parameters.

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 the tool returns Wikipedia's 'today's featured' content for a specific date, enumerating the content types (featured article, most-read, picture of the day, on-this-day events). This distinguishes it from siblings like onthisday and random, which focus on narrower scopes.

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 explicit use cases: 'what's on Wikipedia today', 'featured article on 2026-05-21', and 'to seed daily-roundup content'. It gives clear context for when to invoke the tool, though it does not mention exclusions or alternatives.

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