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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered; the description adds genuinely new behavior: determinism (same input, same output) and hard limits (64 KB JSON input, 1 s per call, 1 MB result). It also states the tool flags common security omissions, which tells the agent what the output is for.

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?

Purpose and exclusions are front-loaded, but the text is doubled in Spanish and English and then repeated a third time inside inputSchema.description, and the generic "Cuándo" list of unrelated artifact types is filler for this tool. It is longer than the task warrants.

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?

For a one-parameter, single-purpose parser with a full output schema and complete annotations, the definition covers scope, exclusions, determinism and resource limits – enough for an agent to call it correctly. The only shortfall is that input edge cases (malformed header, multiple Set-Cookie values) are not addressed.

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 the single parameter already has a type, maxLength, an example and a description, so the schema does the heavy lifting. The prose adds no syntax or format guidance beyond that (e.g. how multi-header input or malformed input is handled); baseline 3 is appropriate.

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 resource: parses a Set-Cookie response header into name, value and attributes, and names the exact attributes handled (Expires, Max-Age, Domain, Path, Secure, HttpOnly, SameSite, Partitioned). It also names the sibling it is not (cookie-parse), so the agent can distinguish it 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?

The exclusion is explicit and routes to the alternative: "No para: analizar el encabezado Cookie (cookie-parse)". However, the "Cuándo" clause is generic boilerplate that lists URLs, tokens, versions, IP ranges, HTML and agent files – content irrelevant to this tool – so the positive usage trigger is weaker than the negative one.

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