vm_capabilities

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false. The description adds the valuable behavioral detail of not acquiring the VM lease, which is not present in annotations. It does not describe return format or edge cases, but given the safety profile already covered, this is sufficient.

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 single sentence, front-loaded with the active verb 'Read', and includes all necessary information without any fluff. It is concise and well-structured.

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 with no parameters and no output schema, the description fully states the action and the key lease-free constraint. The term 'capabilities' could arguably be more specific, but in the VM context and with the sibling tool set, it is sufficiently clear. It is complete enough for an agent to know when and how to invoke it.

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 the input schema is trivially 100% covered. The description cannot add parameter semantics beyond what the schema provides. Per the baseline for zero-parameter tools, a score of 4 is appropriate.

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 the specific verb 'Read' and identifies the resource as 'connected Windows 98 guest capabilities'. The qualifier 'without acquiring the VM lease' distinguishes it from sibling tools that likely require lease acquisition. This leaves no ambiguity about what the tool does.

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 phrase 'without acquiring the VM lease' provides clear usage context: it is a lightweight read that avoids the overhead of lease acquisition. While it does not explicitly name alternative tools, it implies this is the go-to for capability checks when lease-free access is desired. This meets the bar for clear context without exclusions.

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