create_instance

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

No annotations are provided, so the description carries the full burden for behavioral disclosure. It lists parameters and the return value but does not mention side effects such as resource persistence, potential costs, required permissions, or failure behavior, leaving significant operational context undisclosed for a mutating action.

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 description is a well-structured docstring with a clear first sentence, an Args section covering all nine parameters, and a Returns section. Each line is informative and earns its place, though the parameter list necessarily makes the description longer than a simpler 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?

The description covers all parameters and states that a status message is returned, which is useful given the absence of an output schema. However, for a complex create operation with no annotations, it lacks critical operational context such as IAM requirements, cost implications, or what the status message contains on failure, leaving clear 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?

The input schema only provides types and defaults; there are no property descriptions. The tool description fully compensates by explaining each parameter, including examples for zone, machine_type, and source_image, and clarifying optional/default values like network and external_ip. This adds substantial meaning beyond the bare 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 'Create a new Compute Engine instance,' which is a specific verb and resource. However, it does not explicitly distinguish this tool from sibling creation tools such as create_service_account or create_snapshot, though the resource type is clearly named.

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 provides no guidance on when to use this tool versus alternatives like get_instance_details, start_instance, or delete_instance. It only states what the tool does without any mention of use cases, prerequisites, or conditions under which it should be selected.

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