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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds useful context beyond that — the 1-credit cost and the shape of the response (calculated number, English notation, digit counts). However, the output description is largely redundant with the existing output schema, and no limits on input phrasing are disclosed.

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?

Two sentences are an appropriate length, but the name is repeated twice ('Words to Numbers: Words to Numbers converts...'), which is wasted front-loaded space. The credit cost is sensibly placed at the end.

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 one-parameter, read-only conversion tool with annotations and an output schema, the description covers purpose, output shape, and cost. Minor gaps remain around accepted input phrasing (language, hyphenation, 'and' handling) that would matter for malformed inputs.

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 'words' parameter already has a description and an example. The description only restates it as 'Pass written words', adding no syntax, length, or format constraints.

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 and resource ('converts spelled-out number phrases into numeric digits'), which is immediately distinguishable from siblings. It stops short of naming the obvious inverse sibling NumbertoWords, so the differentiation is implicit rather than explicit.

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 — pass written words, get digits. There is no statement of when to prefer this over NumbertoWords, no note about supported phrase formats, and no prerequisites or exclusions.

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