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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, but the description adds real context beyond them: a real signed-in Chrome session, the tab-preserving side effect, and that the response carries page elements and text with matching element numbers. It does not cover failure modes, session lifetime, or interaction with cotlet_browser_close.

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 essential behavior and the 'Call it first' instruction are front-loaded, and the sentences are short. Some phrasing is loose ('Answers the page after it', 'with the same numbers') and the trailing Klean CRM action list is narrow, app-specific content that adds routing value for only one app.

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 return-value burden and does so adequately by describing the visible elements and text returned. For a two-parameter, annotation-covered entry-point tool this is close to complete, missing only error and session-lifecycle details.

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 the schema already documents both `app` and `url`, setting a baseline of 3. The description adds only indirect meaning for `url` through the open-tab-else-new-tab routing rule and says nothing about the `app` override, which is left entirely to 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 states a specific verb and resource: it starts the user's Cloud Browser and opens the given URL, and it explicitly frames itself as the first step ('Call it first'). The distinction from the nearby cotlet_browser_navigate sibling is only implicit, so an agent must infer that this tool bootstraps the session while navigate presumably moves an already-open one.

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?

It gives clear sequencing guidance ('Call it first') and explains the URL routing rule (existing site tab first, otherwise a new tab so the user's tabs stay). It never states when not to use it or names an alternative explicitly, leaving the entry-point distinction to inference.

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