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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, and the description adds genuinely new behavioral context: login cookies auto-attach on matching domains and identity_name can override or force an identity. It does not contradict the readOnlyHint, so no flag. Minor gap: no mention of failure/timeout behavior.

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 core action, followed by two tight sentences that each add distinct information (auto-attach rule, override mechanism). No padding or redundancy.

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 tool whose safety profile is covered by annotations and which has no output schema, the description supplies the key operational context an agent needs (cookie attachment and identity override). It is close to complete, missing only edge-case behavior such as navigation failures.

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%, so the description must carry weight — and it does for identity_name, explaining that it overrides auto-matching or forces a specific identity, which is beyond the bare string|null type. in_workspace is not addressed in the description, but the schema already documents it, and url is self-evident.

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 ('Open a URL in a remote browser') so the agent knows exactly what the tool does. It doesn't explicitly differentiate itself from siblings like browser_navigate_back or browser_attach_identity, but the purpose is unambiguous.

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 automatic cookie/identity behavior and mentions identity_name as an override, which implies when to reach for it. However, it gives no explicit when-to-use versus alternatives (e.g., browser_navigate_back or browser_attach_identity) and no preconditions for choosing an identity.

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