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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description adds real value: deterministic 'oldest first' ordering, pagination bounds, and the meaning of returned fields (skills levels and held_days) is spelled out. It does not discuss rate limits or auth, but for a read-only list tool this is solid added context.

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?

It is front-loaded with purpose before parameters, and every clause carries information, but the entire body is one semicolon-chained run-on sentence that is hard to scan. Dense and non-redundant, yet poorly structured for comprehension.

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 and six parameters, the description does what it should: it defines filters and also explains return-side concepts (total, skills levels, held_days). A clearer statement of the default page size behaviour and offset semantics would close the remaining gap.

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 0%, so the description must carry the full load, and it does: limit range (1-100), offset, status enum values, kind enum values with parenthetical meanings, tag format including the 'topic:<id>' convention, and the exact shape/semantics of skill_below. This is essentially complete parameter documentation embedded in prose.

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 opening clause states a specific verb and resource (list the user's vocabulary), plus ordering ('oldest first') and pagination semantics ('a page of limit entries (1-100) from offset'). It is unambiguous what the tool returns, though it never names a sibling (e.g. word_stats, vocab_add) to differentiate itself 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?

There is no when-to-use guidance, no comparison against alternatives like word_stats or topics, and no stated prerequisites or exclusions. The only cross-reference ('see topics()') explains tag syntax, not tool selection, so usage must be inferred.

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