Alerts and prompts seen so far

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

Annotations already declare readOnlyHint=true, so the safety profile is covered, but the description adds real behavioral context: the data source (BiDi browsingContext.userPromptOpened), the connection-scoped window, newest-first ordering, and the blocking nature of the listed prompts. It stops short of saying whether already-handled prompts remain in the list or how many entries accumulate.

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 scope and contents, then the blocking consequence, then the routing advice. The BiDi event name is the only technical detail and it earns its place by explaining where the data comes from.

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 output schema, the description still conveys ordering and entry type (the four prompt kinds), which is the minimum an agent needs. It does not describe what fields each entry carries (e.g. message text, tab identity), which would be needed to consume the result without probing.

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 description coverage is 100% and the single 'limit' param already documents default 10 and max 50, so the schema does the heavy lifting. The description adds no meaning about limit — e.g. whether it truncates newest or oldest entries — so the baseline 3 applies.

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?

Specific verb (List) plus a precisely enumerated resource (alert / confirm / prompt / beforeunload page prompts) with an explicit scope ('since this server connected') and ordering ('newest first'). An agent can immediately distinguish this read-only inventory tool from browser_handle_prompt, which acts on a prompt.

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 states the mechanism that makes the tool relevant ('a page that shows one of these blocks its script until it is answered'), names the alternative explicitly ('use browser_handle_prompt to accept or dismiss'), and gives a concrete trigger condition ('If a page seems stuck, check here first').

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