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

Annotations already declare read-only, idempotent, non-destructive and closed-world, so the safety profile is covered; the description then adds context the annotations cannot express: no network access, no stored state, determinism, and concrete limits (64 KB input, 1 s per call, 1 MB result). Those limits and the determinism guarantee are exactly the kind of extra operational detail that changes how an agent batches or sizes calls.

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 well front-loaded (purpose, then when, then not-for, then effects/limits), but the entire content is duplicated in Spanish and English, roughly doubling token cost with zero added information for an agent. The structure is good; the redundancy is not.

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 and annotations cover safety, so the description need not explain return values; what remains — purpose, selection criteria, side effects, determinism and size/time limits — is fully covered. Nothing an agent needs in order to call this correctly is missing.

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% and both parameters are already described in the schema, so baseline 3 applies. The description adds extraction semantics (trailing punctuation trimming) that the schema does not convey, but it never mentions the `unique` deduplication flag, leaving parameter behavior entirely to 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?

States a specific verb+resource ("Extrae URLs http(s) y www. de un texto") plus the scoping detail that trailing punctuation and unbalanced closing parentheses are trimmed. It explicitly distinguishes itself from the closest confusable sibling, markdown-links-extract, so an agent can select it without opening any 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" condition (transform/compare/measure text exactly rather than approximately) and an explicit "No para" exclusion naming the alternative tool markdown-links-extract. When-to-use, when-not-to-use and the alternative are all present.

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