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

Annotations already flag destructiveHint=true, and the description reinforces this by disclosing that an empty string wipes the footer. It further discloses non-obvious behavior: the setting is global across invoices and credit notes, output is rendered as up to 3 columns with a 5-line cap per column, and it returns a layout summary. It stops short of saying what happens to lines beyond the cap (truncation vs. rejection) or whether the footer applies retroactively.

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 action and scope, then format rules, a concrete Spanish example, the removal case, and the return value – every part earns its place. It is dense but not padded; the parenthetical keyword variants are the only marginally expendable text.

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, and the description compensates by stating it returns the updated column layout summary. Combined with global-scope disclosure, formatting rules, and the removal path, an agent has what it needs to call it correctly; only edge-case limits (overflow lines, effect on already-issued invoices) remain unstated.

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% with a single well-described parameter, so the baseline is 3 – but the description goes well beyond it by explaining the formatting grammar (blank-line separated blocks become columns, first line is the bold heading, max 3 columns, max 5 additional lines) and the empty-string reset. That is meaning the schema string description does not carry.

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 (set) plus the exact resource and scope: the footer printed at the bottom of every invoice and credit note page. An agent can immediately distinguish this from unrelated invoice operations in the sibling list such as get_invoice_footer or set_invoice_display.

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?

Usage is implied by the 'set' verb and the explicit 'pass an empty string to remove the footer' instruction, which is a useful when-to-use cue. However, it never names the read counterpart get_invoice_footer for inspecting the current footer, nor states any prerequisite (e.g. settings permission) or when-not-to-use condition.

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