list_available_volume_sizes

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

With readOnlyHint=true and idempotentHint=true annotations, the safety profile is already disclosed. The description adds a useful behavioral hint about the parameter source (list_regions), but it does not detail return format, error behavior, or pagination. This adds some value beyond annotations but is not exhaustive.

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 a single, focused sentence with no filler. It front-loads the action and resource, and includes the parameter source in a parenthetical note. Every word 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?

For a simple read-only listing tool with one parameter and no output schema, the description is sufficient. It clearly states what the tool returns and the source of the required input. It could optionally mention its role in the volume purchase workflow, but that is not essential 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 description coverage is 0%, so the description must compensate for the 'pop' parameter. It does so by explaining that it is a Point of Presence id from list_regions, giving the parameter meaningful context beyond the bare schema type. This is valuable and goes beyond what the schema provides.

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 clearly states the action ('List'), the resource ('volume sizes/kinds'), and the scope ('purchasable in a given region'). It is specific and distinguishes itself from siblings like purchase_volume or list_available_os_for_volume by focusing on volume size/kind availability.

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 a clear prerequisite: the region is identified by a Point of Presence id from list_regions. This tells the agent where to get the input parameter. However, it does not explicitly name alternatives or state when NOT to use this tool, so it falls short of an explicit routing guide.

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