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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, yet the description adds genuinely new traits: no network, no stored state, determinism, and hard limits (64 KB input, 1 s per call, 1 MB result). One flaw: the stated 64 KB JSON limit sits uneasily against the schema's 1 MB text maxLength, which could mislead an agent sizing its input.

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?

Each language block is dense and front-loaded (purpose → when → not-for → effects → limits), but the entire content is duplicated verbatim in Spanish and English, roughly doubling length for no informational gain to a single-language reader.

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?

Return values are covered by the existing output schema, so the description only needs purpose, routing, and limits – all present, including determinism and no-side-effect guarantees. The only shortfall is the unresolved 64 KB vs 1 MB input-size inconsistency, which matters for a tool with a required bulk text parameter.

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 baseline is 3, but the description adds semantics the schema does not: case-folding, Unicode segmentation rules, and that stopword lists are specifically English or Spanish. It does not explain 'top' ranking behavior (sorted by frequency, ties by first appearance) in the word-frequency section, so it stops short of a 5.

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 (counts word frequencies) plus the distinguishing mechanics: Unicode word segmentation, case-folding, optional min length, English/Spanish stopword removal. It explicitly names the sibling it is NOT (char-frequency), so an agent can separate the two without opening either schema.

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?

Provides an explicit 'Cuándo'/'When' clause (exact measurement rather than approximation) and an explicit 'No para' pointing at char-frequency. The positive condition is somewhat abstract ('transform, compare or measure exactly'), so the routing value comes mostly from the exclusion rather than a concrete trigger.

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