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

The annotations already declare readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds two genuinely useful facts beyond that: the output content is in Dutch and it mirrors the tachtien.nl entry. It says nothing about length or caching, which is acceptable given the low-risk read profile.

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 tight sentences with zero filler. The target word and the returned fields are front-loaded, and the output-language note is a short, purposeful trailing sentence.

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?

An output schema exists, so return values need no explanation, and the description still previews them helpfully. For a fixed-target, parameterless lookup this is essentially complete; only the implicit 'this tool always defines tachtien' framing could be made more explicit.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline is 4. One small missed opportunity is stating explicitly that no word argument is accepted, which would stop an agent from attempting to define other terms.

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 names a specific verb (define) and a specific resource (the Dutch word 'tachtien'), and enumerates the fields returned: syllables, part of speech, IPA, definition and origin. That is enough to distinguish it from 'examples', 'mentions' and 'tachtienify', though no sibling is named explicitly.

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?

Usage is only implied: an agent infers it should call this when it wants the dictionary entry for 'tachtien'. There is no statement of when not to use it, no pointer to the sibling tools for usages/mentions, and no note that the target word is fixed rather than passed in.

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