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

Annotations already declare readOnlyHint=true, openWorldHint=true, destructiveHint=false, so safety is covered. The description still adds genuinely useful behavior: a real Chrome where the user is signed in (auth context), and tab-targeting rules ('The URL goes to the site's open tab, else to a new tab, so the user's own tabs stay'). The description itself is strong here; the 3 reflects that annotations carry much of the load, though the tab-routing and return-shape details go beyond them.

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 essential action and ordering, then return shape, then use cases; every sentence is compact. The trailing Crexi action list is somewhat enumerative filler that would apply to many browser tools, mildly diluting focus.

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 usefully covers what comes back ('the elements and text in view, with the same numbers'), and it explains the session/auth context and tab behavior. For a two-parameter, zero-required tool, an agent has enough to call it correctly.

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 is 3, but the description adds real semantics for `url`: it explains where the URL lands (existing site tab, else a new tab). The `app` parameter is only explained in the schema, keeping this below 5.

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 ('Starts the user's Cloud Browser ... and opens `url`') plus a sequencing cue ('Call it first'), so an agent knows this is the entry point. It stops short of explicitly distinguishing itself from the sibling cotlet_browser_navigate, so 4 rather than 5.

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 guidance, and the Crexi action list names concrete scenarios where this entry point is used. It doesn't say what to do when a browser session is already open (e.g. whether to use navigate instead), leaving one gap.

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