aws_stop_instance

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

No annotations provided, so description carries full burden. It discloses that disk state is preserved, EBS billing continues, instance-hours pause, and the instance is restartable. However, it doesn't mention possible limitations (e.g., instance-store instances cannot be stopped) or IAM permission requirements.

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, no redundant words. All necessary information is included in a compact, front-loaded manner.

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 simple stop action, the description covers behavior (disk, billing, outage), confirmation requirement, and prerequisites (EBS-backed). No output schema is needed, and the description is sufficient for correct invocation.

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%, so baseline is 3. The description adds no extra detail about parameters beyond what the schema already provides. It does not explain the format or constraints of instance_id or region.

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 starts with a clear verb 'Stop' and specific resource 'AWS EC2 instance'. It adds clarifying details ('EBS-backed; restartable') that distinguish it from siblings like reboot, start, or terminate.

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?

Explicitly states when to use: 'Stop a running AWS EC2 instance'. Provides a clear warning: 'Confirm with the user — outage until the instance is started again', which acts as a when-not-to-use hint.

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