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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered; the description adds genuinely new behavioral context that annotations do not carry: cookies are silently attached on domain match, and the result's `identity` field reveals which saved login was used (null = anonymous). It stops short of describing navigation failure behavior or tab handling.

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?

Three compact sentences, front-loaded with the core action, followed by the non-obvious identity behavior and the return-field semantics. There is no filler and no repetition of the tool name.

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 and only three parameters, the description covers what is hardest to infer: cookie/identity resolution and the `identity` result field. It omits whether the call opens a new tab, how navigation errors surface, and how it relates to the other browser_* navigation tools, which leaves minor gaps.

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 only 33% and identity_name has no schema description, so the description's explanation of override versus force semantics for that parameter is valuable. It does not explain in_workspace (covered by the schema) or add format details for url, leaving the compensation partial for a low-coverage 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?

"Open a URL in a remote browser" names a specific verb and resource, so the agent knows this is the navigation entry point rather than a click or snapshot action. It does not, however, distinguish itself from siblings like web_fetch or browser_navigate_back, which an agent could easily confuse with it.

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?

The description explains the identity selection behavior well (auto-attach on domain match, identity_name to override or force), which implicitly tells the agent when to supply the override. It gives no guidance on when to use this tool versus web_fetch for fetching content or browser_navigate_back for history navigation, so the choice among siblings is left to inference.

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