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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the upstream data source (Datamuse API) and a cost signal ('cost: 1 credit'), which helps an agent budget calls. It does not say anything about result ordering or match quality, which keeps it below 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 tight sentences with the core purpose front-loaded, followed by the trigger condition and then the source/cost note. No filler or repetition of the title.

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 rich annotations and full schema coverage, the definition supplies purpose, trigger, source, and cost — enough to invoke correctly. The only minor gap is that nothing characterizes the output (a ranked word list) or how the credit is charged, but with no output schema required this is largely 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 description coverage is 100% and both parameters (limit with range and default, description as required meaning string) are fully documented in the schema. The description adds no syntax or formatting guidance 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?

The description opens with a specific verb-and-resource framing: a 'reverse dictionary tool that finds words matching a description or concept.' That is clearly distinct from sibling tools such as word_definition (forward lookup), synonyms_for_word, words_that_rhyme, and words_sounding_like, and the follow-up sentence pins down the exact use case.

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?

'Ideal when you know the meaning but have forgotten the specific word' gives a concrete, recognizable trigger condition. It falls short of naming alternatives or when-not-to-use rules — nothing tells the agent to prefer word_definition or synonyms_for_word for adjacent needs — so it is clear context without explicit exclusions.

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