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

The annotations already establish readOnlyHint=true and destructiveHint=false; the description reinforces this by explaining why (it only returns instructions and opens nothing), which resolves what would otherwise look like a contradiction for a 'create invoice' tool. It also discloses that no API execution path exists unless the paid API add-on is purchased, adding value beyond the annotations. Idempotency and open-world behavior from the annotations are not discussed.

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 core behavior and the browser handoff are front-loaded and clear, but the closing paragraph about the official API's variable pricing (with a dated 'checked' stamp) is tangential and slightly bloats an otherwise compact definition. The parenthetical 'screens, buttons, fields' detail is useful.

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 zero-parameter, no-output-schema tool, the description covers what an agent needs: what it returns, that it performs no action, and which tools to use next. It could go slightly further on prerequisites (e.g., an active authenticated Cloud Browser session) before the browser step.

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 and the schema is fully specified, so the description carries no parameter burden. It correctly describes no inputs, matching the empty schema without adding noise.

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 states a specific action (create/send/charge an invoice) and — more importantly — clarifies the actual behavior: it returns step-by-step instructions rather than performing the action. This distinguishes it from a tool that would do the work, though it does not explicitly name or contrast with siblings such as add_or_charge_a_package_on_a_client's_account.

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 explicit sequencing guidance: call this first, then execute with the cotlet_browser_* tools in the user's Cloud Browser, and it warns that the tool 'opens nothing by itself.' It lacks a when-not-to-use clause or sibling comparison, which keeps it below a 5.

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