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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the description's added value is the return shape (deduplicated words plus their source lists) and the scoping rule that only English lists are grade-placed. The caveat that grade is a guide rather than an assessment is meaningful behavioral context an agent would otherwise have to guess. It stops short of noting ordering or truncation behavior beyond the schema's limit.

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 sentences, front-loaded with what is returned, then the optional filter, then the grade caveat. No sentence is redundant and the most decision-relevant information comes first.

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?

There is no output schema, so the description carries the burden of describing the response, which it does (deduplicated words with source lists). Combined with the grade/language scoping caveat, an agent has enough to call it correctly; only pagination/ordering detail is absent.

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 67%, and the description fills the notable gap by giving meaning and examples for the undocumented 'section' enum and by framing 'grade' as a curriculum guide rather than a strict rule. The 'limit' parameter is left to the schema, which already documents its default and bound.

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 opening clause states a specific verb and resource — every distinct English word across the lists covering a grade, deduplicated, with per-word list provenance. It implicitly separates itself from single-list siblings (get_word_list) and search siblings (find_words) by describing aggregation across lists, but never names them.

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 optional section filter is illustrated with examples ('only sight words or only cvc'), which implies when to use it. However, there is no explicit statement of when to choose this tool over get_word_list or find_words, and no when-not guidance, so usage is only implied.

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