system_info

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

Beyond the annotations (readOnlyHint, idempotentHint), the description discloses a significant behavioral trait: the VM remains locked by this session and requires vm_unlock. This is not captured by the annotations and is essential for safe usage.

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 sentences, front-loaded with the purpose, then the lock caveat. No redundant information; every clause earns its place.

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?

Given the zero-parameter schema and no output schema, the description fully covers the tool's purpose and the necessary side-effect behavior (lock state and unlock requirement). No missing critical context.

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, and the schema is empty. The description does not need to add parameter details; the baseline for a zero-parameter tool is satisfied.

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 a clear verb ('Read') and specific resources ('guest operating-system, code-page, display, and build information'). It distinguishes itself from sibling tools about system control (reboot/shutdown) and status checks by focusing on detailed read-only guest information.

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 explicit context for when to use the tool (when needing guest system information) and includes a critical follow-up instruction ('call vm_unlock when finished'). However, it does not explicitly mention alternatives or exclusions, though the lock caveat strongly guides correct usage.

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