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

Annotations only say readOnlyHint=false and openWorldHint=false. The description adds substantial behavioral context: it returns a link where the sender reviews, completes, signs and pays; it does not charge or send until payment happens on the web; it handles missing data with [DATO PENDIENTE] placeholders; and it explains sharing behavior. No contradiction with annotations.

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 core action and return link, and every sentence carries operational meaning (pricing, placeholder handling, sharing, no-charge guarantee). It is somewhat dense and long, but not redundant for a tool with this much conditional behavior.

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 9-parameter tool with no output schema and minimal annotations, the description covers the key behavioral contract: what it prepares, what link it returns, that payment happens externally, and how to handle missing data. Minor gaps remain around link expiry or error behavior, but an agent has enough to invoke 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 description coverage is 100%, so the baseline is 3. The description mostly restates schema-level semantics (borrador_token, texto, compartir) without adding format or constraint details beyond what the schema already documents. It clarifies usage flow but not parameter syntax.

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 ('Deja un burofax listo para enviarse en papel con acuse de recibo') and distinguishes itself by naming the sibling redactar_burofax as the source of borrador_token. An agent can tell this prepares a certified mailing and returns a payment/signing link, separate from tools like estado_envio or listar_casos.

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?

Gives clear conditions: use with a borrador_token from redactar_burofax or with own texto, and pass compartir:true when another person will sign and pay. It does not explicitly state when not to use this tool or compare it to estado_envio/listar_casos, but the context is unambiguous.

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