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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the description's main value-add is the explicit cost disclosure (0.10 USDC per call), which is genuinely useful behavioral context absent from structured fields. It does not add anything about response shape or rate limits, but the paid-call warning is the important bit here.

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 tight sentences with the cost warning front-loaded and the resource description immediately after. No filler, no repetition of schema fields.

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?

An output schema exists so return values need not be explained, and annotations cover the safety profile. The gap is the '(AWS or Azure)' scope claim, which contradicts the schema's gcp enum value and could cause an agent to skip valid GCP calls, plus no routing guidance among the many snapshot siblings.

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 region and provider are fully documented in the schema and the baseline is 3. The description adds no format detail, and it introduces a mild inconsistency by saying '(AWS or Azure)' while the schema's provider enum also allows gcp.

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 names the specific resource (reserved effective hourly price) and scope (every instance type and ri_type in a region), so an agent can tell what it returns. However, it never differentiates itself from the sibling `reserved` or from the other snapshot tools (ondemand_snapshot, spot_snapshot, gpu_snapshot), leaving sibling selection to inference.

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?

There is no statement of when to use this tool versus `reserved`, `ondemand_snapshot`, or `spot_snapshot`, nor any prerequisites or exclusions. The only usage-adjacent signal is the pricing note, which is not guidance about selection.

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