Retrieve all IPv6 addresses assigned to a Vultr instance by its ID, label, or hostname.
List IPv6 addresses for an instance.
Args: instance_id: The instance ID, label, or hostname (e.g., "web-server", "db.example.com", or UUID)
Returns: List of IPv6 addresses
| Name | Required | Description | Default |
|---|---|---|---|
| instance_id | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v1.0.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral burden. The verb 'List' and the Returns section imply a read-only operation and specify the output type, but it does not disclose pagination, auth requirements, or behavior for unknown/invalid instance IDs. It is adequate for a simple read tool but not rich.
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 compact and well-structured with a clear intro, Args section, and Returns section. Every sentence adds value, and the parameter explanation is front-loaded. No filler or redundant elaboration.
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 single-required-parameter list operation with an output schema, the description covers the essential semantics: what is listed and how to identify the instance. It lacks usage guidance and some behavioral detail, but nothing an agent needs to perform this basic call is critically missing.
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 0%, and the description fully compensates by explaining that instance_id can be an ID, label, or hostname, with concrete examples like 'web-server', 'db.example.com', or UUID. This is exactly the semantic detail an agent needs beyond the bare string type.
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?
Description opens with a specific verb and resource: 'List IPv6 addresses for an instance.' This clearly distinguishes it from the sibling instance_list_ipv4 and other instance operations by target address family. The scope is immediately understandable without needing to inspect the schema.
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 when-to-use or when-not-to-use guidance is provided. The sibling instance_list_ipv4 is the obvious alternative, but the description never explains how to choose between listing IPv4 vs IPv6 addresses or mentions any caveats such as instances without IPv6 enabled.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.