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

The annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, and the description reinforces this with 'opens nothing by itself', which is exactly the reassurance an agent needs given the misleading 'create' verb. It also adds valuable negative knowledge — no public API, no API keys, no developer docs — which stops the agent from trying an API route. It stops short of describing what the returned steps look like in detail or whether an open cloud-browser session is a prerequisite.

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?

The description is front-loaded with the actual behavior ('returns how to do it step by step') and puts the critical negation ('opens nothing by itself') immediately after, before the API caveat. The parenthetical '(checked 8 Nov 2026)' is a minor tax, but the API note earns its place by preventing a wrong approach.

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?

With no parameters and no output schema, the description carries the burden of explaining both the return value's nature and the follow-up action, and it does both. It could be tighter on prerequisites (e.g., that a Cloud Browser session must be opened first), but an agent has enough to call it correctly 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?

The tool takes zero parameters, so the baseline is 4 and there is nothing the description needs to disambiguate. The schema coverage is 100% and empty, so no compensation is 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?

The description names the concrete resource (an invoice in the user's own Invoice Simple account) and, crucially, clarifies that the tool does not actually create anything — it returns step-by-step instructions. The only friction is that the headline verb 'Create invoice' conflicts with 'opens nothing by itself', so the agent must read past the first clause to learn the real behavior.

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?

It gives an explicit downstream workflow: take the returned steps and execute them with the cotlet_browser_* tools inside the user's Invoice Simple Cloud Browser. It does not explicitly differentiate itself from the sibling cotlet_app_guide, which could plausibly supply overlapping guidance, but the Invoice Simple-specific framing makes the intended use clear.

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