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

Annotations only supply readOnlyHint/openWorldHint, so the description carries the real burden — and it does, disclosing the entry fields returned (headword, transliteration, POS, senses, etymology, source lexicon like LSJ/Autenrieth) and the occurrence cap of 10 with context/gloss/citation/link. It stops short of describing error behavior for unsupported languages or the lexicon-selection logic.

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, front-loaded with the core action and the acceptable input forms before the return description. The second sentence is dense with parenthetical lists and runs long, but nearly every clause carries information an agent needs given there is no output schema.

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 enumerating the entry structure and the per-occurrence payload (context line, gloss, citation, reader link) plus the 10-occurrence cap. Combined with the input-form guidance and the named source lexicons, an agent has enough to call this correctly and interpret the result.

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 adds real meaning beyond the schema's bare example list: it specifies that `word` may be accented or inflected and that results are original-language lexical entries. It says nothing about the `book` parameter's precedence behavior, leaving that entirely to the schema.

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 states a specific verb and resource ('Looks up an original-language word') and narrows the domain to Ancient/Koine Greek lexicon lookup, which separates it in spirit from the generic `search` sibling. It never explicitly contrasts itself with `search` or `get_passage`, so the differentiation is implicit rather than stated.

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?

It gives concrete input-shaping guidance: accents are tolerated, dictionary forms work best, inflected forms usually work. It does not say when to reach for this tool instead of `search` or `get_passage`, nor what happens with non-Greek input, so no exclusions or alternatives are covered.

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