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

Annotations already declare readOnly, idempotent, closedWorld, non-destructive, so the safety profile is covered; the description still adds real value with determinism, absence of stored state, and concrete limits (64 KB input, 1 s per call, 1 MB result). "No network access" duplicates openWorldHint=false, keeping it from a 5.

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?

Front-loaded with the verb + algorithm and organized into clearly labeled sections (When / Not for / Side effects / Deterministic / Limits). The full Spanish-plus-English duplication doubles the length, which is defensible for accessibility but is still redundancy.

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 an output schema present and rich annotations, the description fills the remaining gaps: determinism, resource limits, and the sibling it replaces. An agent has everything needed to call it correctly.

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 lacks: the prefix scale default of 0.1, the cap of 4 prefix characters, and the note that the metric suits short strings. It does not explain case_sensitive behavior, so not 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 and algorithm ("Calcula la similitud Jaro y Jaro-Winkler"), gives the output range (0-1) and the intended input domain (short strings like names), plus the prefix-scale configuration. An agent can distinguish it from hash/compare siblings immediately.

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?

Explicitly contrasts with levenshtein-distance ("No para: calcular la distancia de edición..."), which routes the agent away from the most likely confusion. However the positive "Cuándo" clause is generic boilerplate ("transformar, comparar o medir un texto con exactitud") and no other similarity siblings (dice-similarity, damerau-levenshtein, hamming-distance) are addressed.

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