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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so the safe-read profile is covered. The description adds genuinely new behavior context: the one-time-payment model (no subscription), the 14-day refund policy, and the constraint that no purchase action can be taken here.

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?

Content is front-loaded: what is returned first, then when to use it, then the alternative, then the constraint. Only the final sentence ('No tiene parámetros') fails to earn its place, since the empty input schema already conveys this.

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, the description fully enumerates what the agent will receive (tiers, prices, inclusions, guarantee, URL), and with no parameters there is nothing else an agent needs before calling it. Nothing material 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?

The tool takes zero parameters, so there is nothing for the description to clarify; the baseline for a non-parameterized tool is 4. The closing note that it takes no parameters is harmless but redundant with the empty 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?

Specifies the exact resource returned (course tiers) and its scope: price in euros, one-time payment model, what each tier includes, refund guarantee, and the plans-page URL. It clearly separates this tool from siblings by naming mi_cuenta as the source for what the user already owns.

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?

Explicit trigger conditions ('when the person asks about prices, which tier to buy, or what each includes'), an explicit alternative (mi_cuenta for current entitlements), and a clear boundary that purchases happen on the web and cannot be completed through this tool.

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