instance_create

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

With no annotations, the description carries full burden. It discloses automatic auth cloning and isolation. However, the phrase 'automatically cloned' could be misinterpreted as always happening, though the cloneAuth parameter allows disabling it, creating slight ambiguity.

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 short sentences efficiently convey purpose, key behavior, and state isolation. No wasted words, front-loaded with the most important action.

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?

The description covers core purpose and behavior, but lacks explicit information about the return value or confirmation of success. Given no output schema, the agent might benefit from knowing what happens after creation (e.g., the instance ID or status).

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 parameters are already documented. The description adds context about auth cloning behavior but does not substantially enrich understanding of individual parameters (instanceId, url) beyond 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 clearly states the verb ('Create') and resource ('new isolated browser instance'), and explains key differentiating features (auth cloning, isolation). It distinguishes itself from sibling tools like browser_connect and instance_close.

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 implies usage when a new isolated instance with cloned auth is needed, but does not explicitly state when not to use it (e.g., if no isolation required) or mention alternatives among siblings.

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