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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, so the safety profile is partly covered. The description adds genuinely non-structured behavior: every person created counts toward the monthly charge, which materially affects whether an agent should call it casually. It omits duplicate/existing-WhatsApp behavior and any confirmation of what is returned, which matters given idempotentHint=false.

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 what it does, then the trigger example, all in a couple of sentences with no padding. The trailing English sentence duplicates the Spanish content, which is mild redundancy but plausibly serves cross-language routing.

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 3-parameter creation tool with annotations and no output schema, the definition covers action, trigger, billing side effect and the site's scheduling role. The main residual gap is duplicate handling and error behavior, which an agent would want before calling a non-idempotent create.

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?

With 67% schema coverage, the schema already explains sitio, empresa, nombre and whatsapp formats. The description restates the WhatsApp format (10 digits Mexico or international prefix) and the site assignment without adding much beyond it, and says nothing about the optional 'codigo' parameter or the 100-person cap.

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 gives a specific verb+resource: creates one or more people with name and WhatsApp and assigns them to a site, plus the batch ('una o varias personas') and billing consequence. It doesn't name a sibling (e.g., asignar_empleado_a_sitio for moving an existing employee, or desactivar_empleado for removal), so differentiation from the closest alternatives is left implicit.

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 supplies a clear positive trigger with a realistic utterance ('agrega a Luis Pérez, 8112345678, a la obra norte'), which is exactly what an agent needs to route natural-language add-employee requests here. It stops short of exclusions — no statement of when to use asignar_empleado_a_sitio or desactivar_empleado instead, and no mention that duplicates may need a different path.

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