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

Annotations already declare readOnlyHint=true, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the meaning of the 'source' field and the convention that an absent or null feature key means SIN TOPE, which an agent could not infer otherwise.

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 purpose, then a bulleted trigger list, then a return-field enumeration. Every sentence carries information, though the return-field paragraph is dense and could be tightened slightly without losing meaning.

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 no output schema present, the description takes on the burden of explaining the return payload and does so fully: plan_id, plan_name, source, started_at, and the features object with both boolean flags and numeric caps plus the null-means-unlimited convention. Nothing an agent needs to interpret the result 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?

There are zero parameters, so the baseline is 4 regardless of schema coverage. The description correctly adds no parameter detail and focuses its space on return semantics instead.

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 (obtiene el plan de suscripción del usuario) and enumerates the possible values (Free, Hobby, Pro) plus what it covers. This makes it clearly distinguishable from adjacent tools like get_settings, get_me, or get_storage_usage 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 three concrete trigger questions, including the conditional case '¿puedo hacer X?' where the answer depends on the plan, which implicitly separates it from usage-metering tools. It does not explicitly name alternatives or exclusions, so it falls short of a full 5.

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