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

Annotations already declare read-only, idempotent, open-world, non-destructive behavior. The description adds genuinely new context: the corpus size (5,600+), the licensing/cost ('Free, 0 credits'), and the per-entry URL return shape, which helps an agent budget calls.

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, zero filler, scope and routing guidance front-loaded before the next-step pointer to wex_define.

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?

For a read-only paginated list tool with strong annotations and no output schema, the description covers what is being listed, how to page, and the follow-up tool. Only the sibling distinction against wex_search is left implicit.

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%: limit (default 100, max 500), letter (single a–z or specific digits), and offset are all documented in the schema. The description only alludes to paging, adding no format or boundary detail beyond what the schema already provides, so the baseline 3 applies.

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?

States a specific verb+resource: listing Wex legal-encyclopedia entries under one letter of its A–Z index, including total corpus size and that each entry carries a URL. It is clearly distinguishable from wex_define (definition lookup) and wex_search (query-based retrieval).

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?

Gives concrete usage contexts ('enumerating terms or paging through a letter') and routes the agent to the sibling wex_define for definitions. It does not contrast itself with wex_search, which is a plausible alternative for the same corpus, so it falls short of full when/when-not coverage.

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