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

Annotations already declare readOnlyHint/destructiveHint/openWorldHint/idempotentHint, so the safety profile is partly covered, and 'Read-only' repeats that. The description earns credit for genuine additions: masking and redaction of sensitive fields unless Developer mode is 'Allow all', and the prompt-injection warning that page content is untrusted text. It doesn't describe latency or when the image fails to match observed elements beyond the conditional 'when the image matches'.

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?

Four sentences, all front-loaded with purpose first, then mode behavior, then security constraints. It is information-dense with little waste, though 'Read-only' duplicates the annotation and could be dropped.

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 correctly explains what comes back (image content surfacing via the next task_state in screenshot/combined modes) plus redaction and untrusted-content caveats. The main gap is that the non-image modes an agent would select from the enum are not characterized.

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 only 25%, so the description must compensate, and it does so only partially: it clarifies the behavior of screenshot/combined modes and ties sensitive_category to redaction/masking. Scope (full-page vs relevant-region) is mentioned only glancingly as 'a full-page view', and lite/accessibility/dom modes and the practical difference between them go unexplained.

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 ('request a fresh observation of the task's current page') and immediately delimits it with 'without acting on it', which separates it from action-oriented siblings like browser_run. The modes and content types it can return are named, so an agent knows what it's asking for.

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?

The description explains the operational context (a fresh observation, with task_state returning image content for screenshot/combined modes) and gives an explicit when-not for sensitive_category: 'Never for general reading, summaries or listing page text.' It does not explicitly name alternatives like task_state vs browser_run, so it falls short of a full routing guide.

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