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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds value by clarifying that non-English lists carry no grade and that grade placement is not an assessment, but says nothing about result volume, pagination, or ordering. Reasonable but not rich for the lower annotation bar.

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?

Returned fields and filters are front-loaded, and the grade caveat is placed after the operational content where it belongs. It is slightly longer than needed, with the 'typical guide, not a rule' point repeated in spirit, but no sentence is wasted.

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 no output schema, the description compensates by listing the returned fields, and all three optional enum parameters are covered at 100% schema coverage. The grade-placement semantics fill the main conceptual gap; only result ordering/pagination is left unaddressed, which is minor for a small read-only catalog tool.

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%, so the baseline is 3, but the description goes beyond the schema by stating that English lists are placed by grade while other languages follow their own curriculum and have no grade — meaning a grade filter implicitly excludes non-English lists. That interaction is not obvious from the enum descriptions alone.

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?

Opens with a specific verb+resource ('Lists the available word lists') and enumerates the returned fields (id, title, language, section, grade range, placement source, word count), which clearly separates it from the singular get_word_list and find_words. It stops short of naming a sibling explicitly, so it lands at clear-but-not-differentiated.

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?

Explains the three filtering axes and the semantics behind the grade filter ('English lists whose grade range includes it'). It gives a clear usage context and caveat (grade is a guide, not a rule), but offers no explicit when-not or pointer to an alternative tool.

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