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

Annotations already declare readOnlyHint, openWorldHint, non-idempotent and non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior: the URL lands in the site's existing tab rather than hijacking the user's tabs, and the call returns the page's visible elements and text with consistent numbering — context the annotations cannot express.

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?

The core behavior and the "call it first" instruction are front-loaded in the opening sentences, with no wasted framing. The trailing AnyList action enumeration is somewhat list-heavy and partially duplicates what the anylist_* sibling tools already convey, costing a little density.

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?

For a two-parameter entry-point tool with no output schema, the description covers what is launched, which tab receives the URL, when to invoke it, and what comes back (visible elements and text). Nothing an agent needs in order to call it correctly and interpret the answer is missing.

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 description coverage is 100% and both parameters are documented there, so the schema carries the load. The description reinforces `url` semantics (it goes to the site's open tab, else a new tab) but says nothing about the `app` slug parameter, which is the more surprising one; no value is added beyond the schema.

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?

The description uses a specific verb and resource ("Starts the user's Cloud Browser ... and opens `url`") and immediately explains what the Cloud Browser is (a real Chrome where the user is signed in). It distinguishes itself from the surrounding browser siblings by stating it must be called first, so an agent can pick it out without opening other schemas.

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 an explicit ordering rule relative to the other browser tools, and the AnyList sentence names the concrete tasks this entry point serves. It stops short of naming an explicit alternative (e.g. when to use cotlet_browser_navigate instead of opening a URL here), so it is strong but not fully exclusionary.

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