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

With no annotations, the description carries the disclosure burden and does well: it states the owner-only permission requirement, that exactly one email is sent (not a recurring cadence), the default delay, the sending address, and where replies go. It does not say whether turning it on applies to invoices already sent or whether scheduled reminders are cancelled when turned off.

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?

Three sentences, front-loaded with the action and its scope, then the behavioral effect, then the delivery detail. No sentence is redundant and nothing is buried.

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 toggle with no annotations and no output schema, the description covers the essentials: permission, effect, timing, and sender identity. The remaining gap is retroactivity and what the call returns, which is a minor omission rather than a blocker.

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 only 33% (only delay_days is documented), so the description must compensate. It does: 'on or off' gives meaning to `enabled`, and 'a set number of days (default 1) after an invoice or deposit request is sent' restates delay_days with its trigger event. `shop_id` is a self-evident UUID with no added semantics needed.

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 ('Turn the automatic unpaid-invoice reminder on or off') with explicit scope ('for the whole shop'). The shop-wide scope implicitly separates it from the per-invoice sibling invoices_setReminder, though that sibling is never named.

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 the owner-only prerequisite and the shop-wide scope, which implies when this is the right tool. It never explicitly contrasts with invoices_setReminder (per-invoice) or says how to inspect the current setting, so the routing decision is left partly to inference.

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