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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds meaningful context beyond that: it tells the agent the response is scoped to the signed-in user's companies and includes role, subscription state, timezone, and active counts — useful because there is no output schema.

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?

The content is front-loaded and every clause in the first sentence describes a distinct returned field. The trailing English sentence ("Companies the signed-in user manages in Chato.") largely restates the Spanish opening, so a small amount of space is not earning its place.

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-argument listing tool with no output schema, the description fully covers what an agent needs: what is returned, how items are scoped, and when to reach for it. Nothing required to call it correctly 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 no parameter semantics to explain and the baseline of 4 applies. The description correctly avoids inventing filtering options the schema does not support.

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 the resource precisely ("Las empresas del usuario en Chato") and enumerates the returned fields — role (propietario, administrador, usuario, solo lectura), subscription/trial status, timezone, and active site/employee counts. It is clearly distinct from the sibling tools, which deal with employees, sites, and shifts, though it never names a sibling explicitly.

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 gives explicit entry-point guidance: "Úsala primero cuando no sepas con qué empresa trabajar o para confirmar que la cuenta está conectada." That covers the main when-to-use cases but offers no explicit when-not or a named alternative, so it stops short of the top score.

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