instance_stop

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

With no annotations provided, the description itself must disclose behavior. It clearly states the state transition (running -> stopped) and the expected return message, but it does not disclose side effects such as workload interruption, whether it is safe to call on an already-stopped instance, or any permissions or billing implications.

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 short, scannable, and front-loaded with the core action. The Args/Returns layout is easy to parse, but the ctx line is unnecessary and inconsistent with the schema, and the Returns line partly duplicates what an output schema would already convey.

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 one-parameter state-changing tool, the description gives enough to invoke it: the identifier forms and the confirmation response. However, because there are no annotations and no side-effect caveats, it is not fully complete for an AI agent deciding whether stopping is the right action.

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 description coverage is 0%, so the description must compensate. It does this well for instance_id by explaining it can be an ID, label, or hostname with concrete examples. However, it also documents a 'ctx' argument that is absent from the input schema, which could mislead an agent into passing an unsupported parameter.

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 opening sentence 'Stop a running instance' is a specific verb+resource+state combination, so the tool's purpose is unambiguous. It is clearly distinguished from sibling lifecycle tools like instance_start, instance_reboot, and instance_delete by naming the stop operation and the 'running' state.

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 'running instance' implies this should be used when an instance is active, but there is no explicit guidance on when not to use it or how it differs from instance_delete or instance_reboot. No alternatives are named, so the usage context is only implicit.

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