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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, so the safety profile is largely given. The description goes beyond them usefully by adding hard limits (64 KB JSON input, 1 s per call, 1 MB result) and an explicit determinism guarantee, which annotations do not express.

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 correctly, but the text is duplicated: a full Spanish block followed by a full English block, and the EN text is repeated verbatim again in inputSchema.description. The redundancy inflates the payload without adding information.

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?

An output schema exists, so the enumerated return fields are redundant-yet-harmless rather than required; with annotations, limits, determinism and the sibling exclusion all covered, an agent has everything it needs to call this correctly. Missing only edge-case behavior (e.g. what happens on invalid/empty input) to reach a 5.

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?

Only one parameter and schema coverage is 100% – the schema already documents type, required-ness, the 64-char maxLength and an example. The description adds nothing parameter-specific (no format nuances such as accepting IPv6 zone IDs or bracketed forms), so 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 ('Valida una IP v4/v6') and enumerates the outputs (canonical RFC 5952, expanded, integer, hex, reverse DNS, type), so the agent knows exactly what comes back. It also distinguishes itself from a close sibling by name: 'No para: describir un bloque CIDR (cidr-info)'.

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 an explicit 'Cuándo' section and an explicit exclusion pointing to cidr-info, which is exactly the routing an agent needs against the many CIDR siblings. However, the trigger list is scattershot ('un token, una versión, ... un documento HTML o Markdown'), which muddies rather than sharpens the selection criteria and may cause over-invocation.

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