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

Adds substantial context beyond the annotations: the tool is a guide-only, side-effect-free operation, the real mutation happens through separate browser tools, and the vendor publishes no public API or keys. This is fully consistent with readOnlyHint=true and destructiveHint=false. The API-availability note is exactly the kind of external-fact disclosure an agent cannot infer from structured fields.

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?

Purpose and the key caveat ("opens nothing by itself") are front-loaded, and the semicolon clause efficiently explains the follow-up tooling. The trailing sentence about Invoice Simple's payment integrations is tangential to the send operation and adds length without improving tool selection.

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?

There is no output schema, so the description must explain the return value, and it does: a step-by-step guide covering screens, buttons, and fields. Combined with the browser-tool handoff and the API-availability note, an agent has everything needed to call it and act on the result.

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 schema carries no semantics to compensate for, so the baseline applies. However, the description never addresses the obvious question of how the tool identifies which invoice to send given no input fields, which is a real ambiguity for the caller.

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 ("Send invoice in the user's own Invoice Simple account") and immediately clarifies the actual behavior: it returns step-by-step instructions rather than performing the send. It distances itself from the cotlet_browser_* siblings by explaining the handoff, though it never distinguishes itself from invoice_simple_create_invoice or invoice_simple_mark_invoice_paid, which an agent might reasonably confuse with "send".

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 a clear workflow: call this to get the screens/buttons/fields, then execute with the cotlet_browser_* tools in the Cloud Browser. It also states the exclusion "opens nothing by itself," which sets expectations. It stops short of saying when to prefer this over creating or marking an invoice paid via the other invoice_simple_* tools.

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