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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description still adds real behavioral context beyond them: the result is deterministic per date ('The same date always gives the same proverb') and the tool must not be treated as a forecast. It does not say what happens with a malformed or future date, which keeps it from 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?

Three short sentences, front-loaded with the trigger, then determinism, then exclusions. Every clause carries distinct routing or behavioral information with 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 zero-required-parameter read tool with full schema coverage, an output schema, and complete annotations, the description covers trigger, determinism, alternatives and misuse. Nothing an agent needs in order to call this correctly is missing.

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% and the single parameter already documents the YYYY-MM-DD format and that omitting it means today. The description only reinforces the date-to-proverb determinism, adding little parameter-level meaning beyond the schema, so the baseline 3 applies.

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 (an Akan/Twi proverb of the day) with the exact retrieval condition, and explicitly separates itself from the topic-based sibling proverbs.find. An agent can choose between this and proverbs.find without opening either schema.

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?

Gives both a positive trigger ('without naming a topic, or for a proverb of the day') and explicit exclusions ('Do not use it when a topic or a word is given (use proverbs.find)'), naming the alternative tool. It also rules out an adjacent but wrong intent (horoscope/prediction), which is unusually thorough routing guidance.

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