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

Annotations already declare readOnly, idempotent, closed-world and non-destructive behavior, so safety is covered. The description adds real context beyond that: the auto-detection order when the language is unspecified and what payload each direction produces (category, pronunciation, translations, forms, synonyms). It does not say what happens for an unknown word or an ambiguous match.

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?

A single dense sentence with the core purpose front-loaded, followed by the direction-specific return contents and the fallback rule. It is efficient, though the semicolon-chained clauses make it slightly harder to scan than separate sentences would.

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 only two parameters, no output schema and full annotation coverage, the description covers what an agent needs: what the tool does, both lookup directions, and the language-default behavior. The remaining gap is failure behavior (word not found, ambiguous language), which is a minor omission for a simple read 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 description coverage is 100%, so both parameters are already documented, which sets the baseline at 3. The description does add meaning for 'lengua' by defining the default resolution order when it is absent, but 'paraula' gets no extra semantics beyond the schema examples.

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+resource ('Look up a single word in the Aranese dictionary') and spells out what each lookup direction returns. It implicitly separates itself from a translator by restricting scope to single words, but it never names or contrasts the siblings tradusir_aranes or corregir_aranes.

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 usefully explains the fallback chain when 'lengua' is omitted (oc, then es, then ca), which is genuine usage guidance for the optional parameter. However, it gives no guidance on when to choose this tool over the translation sibling for a single word, which is the main ambiguity an agent would face.

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