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

Annotations already declare readOnly=true, destructive=false, openWorld=true, so the safety profile is covered. The description adds useful context beyond that: the response includes digit counts and locale info, and it costs 1 credit. It doesn't describe formatting options or limits, so a moderate score is fair.

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?

Front-loaded and brief, but the opening redundantly repeats the name twice ('Number to Words: Number to Words is...'). The rest is efficient and each sentence adds information.

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?

With one simple param, an output schema, and annotations covering safety, the description is complete enough to invoke correctly. It could still note sibling direction or output edge cases, but the tool is low-complexity and well covered.

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% for the single parameter, so the schema already documents 'number'. The description adds that any integer or float is accepted, which is a marginal clarification over the schema; baseline 3 applies when the schema carries the semantics.

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 verb (converts) and resource (numeric values into written cardinal words) and adds that it also counts whole/fractional digits. Clear what it does, though it never names its obvious sibling WordsToNumbers to sharpen the distinction.

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?

Usage is only implied by describing the input; there is no explicit when-to-use, when-not-to-use, or pointer to WordsToNumbers or NumberBaseConverter as alternatives. An agent can infer the purpose but gets no routing guidance.

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