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

Beyond the annotations (readOnly, openWorld, non-idempotent), the description discloses authentication context (user signed in to their sites), tab-placement behavior (existing site tab, else a new tab, so the user's tabs stay), and what comes back (elements and text in view, with matching numbers). The non-idempotent hint is implicitly supported by the tab-reuse rule, but no session lifetime or failure behavior is described.

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 action, the "call it first" directive, tab behavior, and the return shape are front-loaded and dense with no filler. The trailing Help Scout action list is tangential to opening a browser and reads as appended routing metadata rather than essential definition.

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, fully documented, annotation-covered tool with no output schema, the description still usefully explains the return payload and the session model, which is what an agent would otherwise lack. Only edge cases (auth failure, whether the session persists) are unaddressed, which is reasonable at this complexity.

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%, so both `app` and `url` are already documented, including the pattern and the "leave it out" default. The description adds a small amount of meaning by explaining where the URL lands (existing site tab vs. new tab) and by tying `app` to `cotlet_app_guide` via the schema text, but nothing substantial beyond that.

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?

"Starts the user's Cloud Browser ... and opens `url`" gives a specific verb and resource, plus the scope qualifier that it is a real Chrome session where the user is already signed in. It does not explicitly distinguish itself from the sibling `cotlet_browser_navigate`, so an agent must infer that this is the session-bootstrap step and navigate is the in-session move.

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" is an explicit ordering instruction that tells the agent where this tool sits in a sequence, which is the key usage decision here. There is no explicit when-not or named alternative (e.g. navigate vs. open), so it stops short of full routing guidance.

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