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

Annotations already cover the safety profile (readOnlyHint, openWorldHint, destructiveHint=false), and the description adds context they don't: it is a real Chrome session with the user's existing logins, existing tabs are preserved, and the call returns the page's visible elements and text using the same numbering as sibling tools. It does not address session lifetime or what happens on failure, which keeps it from a 5.

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?

Front-loaded with the action and the 'call it first' directive, then effect, then return shape. The trailing Angi action list is long but serves as routing context for the agent; the only mildly wasteful part is that it enumerates workflows rather than stating the rule.

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 carries the burden of explaining the return, and it does describe the returned page view and its numbering. For a two-parameter, zero-required setup tool with full annotation coverage, the remaining gap (no output schema, no failure behavior) is minor.

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 both `url` and `app` are already documented, giving a baseline of 3. The description adds real meaning about `url` routing (existing site tab vs. new tab, user's tabs preserved), but says nothing about `app` beyond what the schema's 'Leave it out' text already states.

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 concrete verb and resource: starts the user's Cloud Browser (a real Chrome where the user is signed in) and opens `url`. The tab-routing behavior ('goes to the site's open tab, else to a new tab') makes the effect concrete. It does not, however, distinguish itself from the sibling cotlet_browser_navigate, which an agent could reasonably confuse with it.

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?

'Call it first' gives explicit ordering relative to the rest of the browser tool family, and the Angi action list signals the workflows it enables. There is no explicit exclusion or naming of the alternative (e.g. navigate) for already-open pages, so it stops short of full when/when-not guidance.

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