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

Adds real behavior beyond the annotations: the call is refused and enumerates account sizes when size_id is missing, and the response is returned only after the computer reaches running (blocking semantics). The idempotency guidance partially restates the schema description, and no auth/permission or quota behavior is described.

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?

Four short, front-loaded sentences, each carrying distinct information: purpose, idempotency discipline, prerequisite/error behavior, and return plus follow-on usage. There is no filler or restatement 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 an output schema present, the description need not enumerate return fields, yet it usefully flags the blocking-until-running behavior and the meaning of the returned name. Prerequisite, idempotency, and follow-on workflow are all covered, so an agent has everything needed to invoke correctly.

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% with enums documented, so the baseline is 3; the description still adds procedural meaning by telling the agent to obtain size_id from the user before calling and how to treat the idempotency key across retries. The key-reuse rule largely duplicates the schema's own wording, capping this at 4.

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 first sentence states a specific verb and resource ('Create a persistent Cloud computer') and the term 'persistent' distinguishes it from transient or in-session work. Against siblings like cloud_computer_start, cloud_computer_list, and cloud_computer_delete, an agent can immediately tell this is the provisioning entry point.

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?

Gives concrete pre-call guidance ('Ask the user which size_id to use before calling') and describes the fallback when omitted (refused call that lists available sizes). It also routes to downstream usage ('use that name in subsequent computer tools'), but never states when not to create one or points to cloud_computer_list/info as an alternative for existing machines.

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