Listar facturas

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

readOnlyHint=true already tells the agent this is a safe read, so the description's burden is lighter. It adds the quarter scope and the fact that filters are optional, but says nothing about default period behavior, pagination defaults, or result volume limits — details that only appear buried in the 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?

A single, front-loaded sentence with no filler. It is efficient, though the terseness leaves little room for the usage and behavioral context the tool would benefit from.

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 9-parameter list tool with no output schema and only a readOnlyHint, the description is minimal: it omits pagination behavior, default period, and what a returned invoice record contains. The rich schema descriptions partially compensate, but an agent still has gaps to fill by inference.

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 description coverage is 89%, so the schema already documents nif, tipo, desde/hasta, filas, inicio, numero and periodo. The description adds marginal value by mapping 'emitidas o recibidas' to the tipo enum and 'de un trimestre' to periodo, but no syntax or semantics beyond that. Baseline 3 fits when the schema does the heavy lifting.

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 specific verb and resource ('Lista facturas') plus scope ('emitidas o recibidas de un trimestre') and the existence of optional filters. An agent can tell it lists invoices, but the description does not name the closest siblings (cs_search_invoice_by_number, cs_get_invoice) to distinguish when this enumeration is the right choice.

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?

'Con filtros opcionales' only hints that filtering is possible; it gives no when-to-use rules, no prerequisites, and no routing to alternatives such as cs_search_invoice_by_number or cs_get_invoice. The only implicit guidance is the quarter scoping, which an agent must infer.

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