Ask the user to sign in

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

Adds substantial behavior beyond the annotations: the values never return to the agent, Chrome names the site's real origin in its own window, one field is shown per listed input, and the call blocks until the user answers, cancels, or times out. None of that is derivable from readOnlyHint/openWorldHint/idempotentHint.

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?

Dense but front-loaded with purpose and the safety rule; every sentence carries an instruction the agent needs. It runs a bit long for the number of concepts, but there is little pure filler.

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?

Covers the privacy model, the input-source workflow, the blocking behavior, and the tool's relationship to browser_type. It stops short of saying what the call yields on cancel or timeout, which matters since there is no output schema, but the coverage is otherwise strong.

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 100%, so the baseline would be 3, but the description adds real semantics: fields are shown in the order given, indices come from the latest browser_snapshot, and password inputs surface as input[password]. It does not explain the session_id or timeout_seconds behavior beyond the schema, which is fine.

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 ('Ask the user to sign in on the page in one of the agent's tabs') and explicitly distinguishes itself from the closest sibling: use this 'instead of browser_type' for secrets. An agent can route between the two without opening either schema.

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?

Explicit when-to-use (passwords, verification codes, any secret), explicit when-not (never ask the user to paste a secret into the conversation), and names the alternative (browser_type). It also supplies the surrounding workflow: pull indices from browser_snapshot, then click the sign-in button yourself.

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