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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, and the description largely restates them ("solo lectura, sin red, sin estado guardado", "determinista"), which earns little credit. What it does add beyond structured data is operational limits: 64 KB JSON input, 1 s per call, up to 1 MB result — concrete constraints an agent cannot see elsewhere.

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?

The core analysis statement is front-loaded, followed by clearly labeled clauses (Cuándo / No para / Efectos secundarios / Determinista / Límites). Only the side-effects and determinism lines partly duplicate annotations, which is a minor cost in an otherwise tight, well-structured description.

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 the description need not explain return values, and it correctly focuses on inputs, modes, limits, and routing. The only gap is that the "números o fechas" framing overstates the tool's scope (a single word), which could mildly mislead an agent about what input to pass.

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 the baseline is 3, but the description adds genuine semantics for the optional parameter: supplying an intended stressed syllable makes the tool return the correct written spelling rather than merely analyzing. That behavioral link between the parameter and the output mode is not stated in the schema.

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 states a specific verb and resource with enumerated outputs: syllables, stressed syllable, word class (aguda/llana/esdrújula/sobresdrújula), and RAE accent-rule compliance. It also describes the second mode (given an intended stress, return correct spelling), so an agent understands the tool's full capability without opening the 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?

It provides an explicit exclusion with a named sibling: "No para: separar palabras en sílabas ... (es-syllabify)", which is exactly the routing information an agent needs versus the near-identical syllable tool. The positive "Cuándo" clause is weaker and slightly off-target, since it talks about handling Spanish text, numbers, and dates while the tool only accepts a single word.

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