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

Annotations already declare readOnlyHint/openWorldHint and non-idempotency, so the safety profile is covered by structured fields. The description adds genuinely useful context beyond that: the session is the user's own signed-in Chrome, existing user tabs are preserved via the open-tab-or-new-tab rule, and it returns the page in view with element numbers. It does not cover session lifetime, launch latency, or failure modes when the URL is unreachable.

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 verb and the ordering instruction, then justification, then the tab rule, then the return shape. Mostly tight, though the phrase 'with the same numbers' is slightly opaque and the trailing mHelpDesk action list is a mild tangent for a generic browser tool.

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 correctly compensates by describing what comes back (visible elements and text with stable numbering). Given the trivial two-parameter surface and rich annotations, an agent has everything needed to invoke it correctly; only error/retry behavior is absent.

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 both `app` and `url` are already documented, and the description adds only the behavioral detail that the URL targets an existing site tab or a new tab. The `app` parameter's omission/default behavior is not reinforced in the description, but the schema handles it fully, so baseline 3 is appropriate.

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 what the browser actually is (a real Chrome on Cotlet with the user signed in). The opening/answer pairing and the 'Call it first' framing make it clearly distinct from siblings like cotlet_browser_navigate and cotlet_browser_read.

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?

Explicit sequencing guidance ('Call it first') and a clear statement of what happens to the URL, which tells the agent this is the entry point before any page interaction. It stops short of naming the alternative to use when a browser session already exists, so the navigate-vs-open boundary is left implicit.

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