volume_expandExpand a Longhorn volume to a specified new size to increase storage capacity. Provide the volume name and desired size to resize it without downtime.
Expand a volume to a new size. Longhorn docs: https://longhorn.io/docs/1.12.1/nodes-and-volumes/volumes/create-volumes/
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | ||
| size | Yes |
Changes observed during successful MCP inspections.
v0.1.6Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure, yet it only names the action. It fails to reveal that expansion is an asynchronous/cancelable operation (evidenced by the volume_cancel_expansion sibling), that shrinking is not supported, or that a filesystem resize may be needed afterward.
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?
A single scannable sentence with the action front-loaded and a relevant docs link appended. There is zero filler; it could carry more detail without becoming verbose, but structurally it is clean.
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 mutating 2-param tool with no annotations, no output schema, and no parameter descriptions, one sentence is inadequate. Missing context includes size units, the cannot-shrink constraint, the cancelable async nature, and prerequisites. The docs link partially compensates but the definition is not self-sufficient.
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 explain both parameters, but it only loosely maps 'size' to 'new size' and leaves 'name' to be guessed as the volume identifier. It does not specify the size string format, units (e.g., Gi), or that the value must exceed the current size — all essential for a correct invocation.
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 specific verb ('expand') applied to a clear resource ('a volume') with a concrete outcome ('to a new size'). This distinguishes it from most siblings like volume_create or volume_update_setting, though it does not explicitly name alternatives.
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?
No guidance is given on when to use this tool versus alternatives. It omits prerequisites (volume must exist, attachment state), the constraint that size can only grow, and when the sibling volume_cancel_expansion would apply. The agent must infer usage entirely from the tool name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.