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 severity bar is lower. The description adds useful substance by listing which settings exist and the allowed iva_display values (ninguno | auto | porcentaje | porcentaje_cuota | porcentaje_total), but it never explicitly says it returns the currently configured values or whether unset values have defaults.

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?

It is a single sentence with no filler, but it opens with a descriptive clause and a colon instead of leading with the action, and the parenthetical list of field names makes it dense and hard to scan. Front-loading 'Returns current invoice PDF display settings:' would improve it materially.

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?

No output schema exists, so the description carries the return-shape burden; it does enumerate the fields (iva_display, show_contix_badge, header_phone, header_whatsapp), which largely covers the response. What is missing is the retrieval framing — that these are the current stored values — and any hint about default behavior when options have not been set.

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 zero parameters, the baseline is 4. The description goes beyond that by documenting the enum domain of iva_display, which is a setting value the agent will encounter in the response rather than a parameter.

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 (invoice display options) and enumerates the exact settings involved, but it is phrased as a definition of what display options are ('How invoice PDFs are printed: ...') rather than as an action the tool performs. An agent can infer it retrieves settings, especially alongside sibling set_invoice_display, but the verb is never stated.

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?

There is no guidance on when to call this versus related tools. The clear counterpart set_invoice_display and related readers like get_invoice_defaults and get_invoice_footer are never referenced, so the agent must infer that this is the read side of the pair.

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