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

Annotations already cover safety (readOnly, non-destructive, openWorld), but the description adds real value beyond them: it discloses that only paid plans may adjust the result cap and that each call costs 2 credits. Those are behavioral facts not present in any structured field, though the free-plan default cap is never stated.

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 purpose is front-loaded and the text is short, but it wastes space restating the tool name twice ('Rhyming Words: Rhyming Words finds...'), and the credit-cost note is buried in parentheses 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 two-parameter read-only lookup with a full output schema and complete parameter documentation, this covers what an agent needs: purpose, return shape, cost, and the paid-plan restriction on limit. Only the default cap for non-paid callers is left unspecified.

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%, so both parameters are already documented and the baseline is 3. The description adds only a mild nuance about the limit being a 'maximum' that paid plans can raise, and says nothing about format or constraints on the word parameter.

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 gives a specific verb and resource ('finds matching rhymes for any query word') and states the return shape (list of rhyming words plus total match count). It does not, however, distinguish itself from near neighbours such as Thesaurus, WordPronunciation, SyllableCounter or WordLexiconAnalyzer, so an agent must infer the boundary.

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?

There is no explicit when-to-use or when-not-to-use guidance, and no alternative tool is named. The only conditional information ('Paid plans can adjust the maximum number of rhymes returned') concerns the limit parameter rather than tool selection.

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