get_next_vmid

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is clear. The description adds crucial behavioral context beyond those annotations by explicitly warning that the ID is not reserved and that concurrent users may claim it. This is valuable information that affects how an agent should use the result.

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?

Two short sentences deliver complete and essential information with no fluff. The primary purpose is front-loaded, followed by the key caveat. Every word earns its place, making it easy for an agent to parse quickly.

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 zero-parameter read-only utility with an output schema present, the description is fully complete. It states the core function and the one behavioral nuance that could change how the result is used. Nothing necessary for correct invocation is missing.

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 tool has zero parameters, so there is no parameter semantics to elaborate on. The baseline of 4 applies, and the description does not need to add parameter-level details. It does not waste space describing nonexistent inputs.

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 uses a specific verb ('Find') and resource ('an available VM ID'), making the tool's function immediately clear. It also adds the distinguishing caveat that the ID is not reserved, which differentiates it from any reservation or creation tool. The scope is unambiguous and distinct from sibling tools like list_guests or get_cluster_status.

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 does not state when to use this tool versus alternatives. It does not mention that the tool should be used before creating a VM or that it complements creation workflows. It also gives no guidance on what to do after obtaining the ID. The only contextual hint is the reservation caveat, which is more behavioral than usage-oriented.

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