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

Annotations already declare readOnlyHint=false and idempotentHint=true, so the load-bearing gap is what happens by default — and the description fills it: the current site is replaced unless agregar=true. It also discloses a side effect the annotations cannot convey, namely that the site drives lateness, absence and reminder logic. Missing only operational detail such as permission requirements or what happens to historical attendance tied to the old site.

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 core action and the default/replace distinction, then examples. The trailing English gloss "Assign an employee to a site." merely restates the title and is dead weight, but everything else earns 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 four-parameter mutation with full schema coverage and no output schema, the description covers the decision-relevant behavior: destructive-by-default replacement, the additive escape hatch, and the scheduling consequence. Remaining gaps (ambiguous employee resolution, permission scope) are minor rather than blocking.

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?

Schema coverage is 100% and the schema already explains agregar ("true para sumar el sitio sin quitar los que ya tiene") and empresa (only needed with multiple companies). The description's contribution is the inverse framing — that the default replaces — which is useful but already largely inferable from the flag's schema text, and it says nothing about empleado accepting either name or code.

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 concrete verb and resource ("Cambia o agrega el sitio de una persona") and immediately qualifies the two modes: default replacement vs. additive with agregar=true. It also clarifies the downstream effect ("define su horario para retardos, faltas y recordatorios"), which separates it from schedule-related siblings like actualizar_horario_de_sitio.

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?

Gives concrete usage examples ("pasa a Karla a la obra sur", "Luis ahora cubre también la caseta norte") that map naturally onto the two modes, so an agent can route a request correctly. It lacks an explicit when-not statement or a named alternative tool, but the mode distinction covers the main ambiguity an agent would face.

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