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

With no annotations, the description carries the full load and does well: it discloses that no registration is required, that calling it is effectively idempotent (returns existing status rather than creating a duplicate), and that it also returns explanatory next steps. It doesn't address failure modes, key expiry, or whether the trial key is rate-limited or scoped, which keeps it below a 5.

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?

Three short sentences: what it does, when to call it, and what happens otherwise. The primary action is front-loaded and nothing is redundant — every clause adds decision-relevant information.

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 zero-param onboarding tool with no annotations and no output schema, the description covers the essential contract: it creates the key, explains next steps, and returns existing status when a key is present. It could say more about the shape of the returned key/status, but nothing critical to correct invocation 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 the description needs to disambiguate; the baseline of 4 applies. The description correctly implies the call needs no arguments by relying on 'sin registro' and ambient state (whether a key already exists).

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?

The description names a concrete action and its result — creating a free trial key with no registration — plus the secondary behavior of explaining next steps. The sentence about when another tool reports a missing key makes it immediately distinguishable from the other wyro_* tools that presumably consume the key.

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?

It states the exact precondition for calling it ('solo si Wyro todavía no tiene clave o si las otras herramientas dicen que falta la clave') and how it behaves when that condition is already satisfied (returns the current status instead of failing). This is explicit when-to-use and when-not-to-use guidance rather than implied context.

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