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

Annotations declare read-only, open-world, non-idempotent, non-destructive, but the description adds substantial context they cannot carry: the browser is an authenticated Chrome session, the URL reuses the site's existing tab to preserve the user's own tabs, and the call returns a numbered snapshot of visible elements and text. That is genuine behavioral disclosure beyond annotations.

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 imperative 'Call it first', then purpose, tab behavior, and return shape in a tight sequence. The trailing Planfy action enumeration is somewhat list-like padding, though it does anchor the tool to concrete workflows.

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 supplies the return shape (elements and text in view with matching numbers), the session/auth context, and tab semantics. An agent has everything needed to call it correctly and interpret the result.

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 meaning about the `url` parameter's routing behavior (existing site tab first, else a new tab) that the schema does not state. The `app` parameter's nuance lives in the schema rather than the description, keeping it from a 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 specific verbs and resource: 'Starts the user's Cloud Browser ... and opens `url`', and clarifies what the browser is (a real Chrome where the user is signed in). This clearly distinguishes it from siblings like cotlet_browser_navigate or cotlet_browser_read, which operate on an already-open session.

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 for the browser tool chain, and the schema covers the app opt-out. It does not name specific alternatives (e.g. navigate) or state when-not to use it, so it stops short of full when/when-not coverage.

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