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

The description states 'Get a random number,' implying non-deterministic behavior, while annotations set idempotentHint=true, suggesting the same input yields the same output—a contradiction. The description does not clarify the randomness or how the optional sign parameter affects the result. Annotations already declare readOnlyHint and destructiveHint, but the contradiction undermines transparency.

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, front-loaded with the core action and output, followed by usage guidance. Every sentence adds value, with no redundancy or fluff.

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?

Given the tool is simple (one optional param, output schema exists, annotations provide safety info), the description is mostly complete: it explains purpose, return format, and usage context. The only gap is the unresolved contradiction between randomness and idempotency, which leaves agents unsure about determinism.

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 describes the single optional parameter 'sign' with an enum and a humorous description. Schema coverage is 100%, so the description adds no additional parameter meaning. Baseline score of 3 is appropriate as the schema handles semantics adequately.

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 gets a random number (1-100) with astrological justification, specifying the verb 'get', the resource 'random number', and the unique context of Mercury's zodiac position. It distinguishes itself from the sibling tools, none of which are number generators.

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 explicitly says 'Use when you need a number with Mercury retrograde insights or cosmic reasoning,' providing clear guidance on when to use the tool. However, it does not explicitly mention when not to use it or compare to alternatives, though no alternative number tool exists among siblings.

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