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

Annotations already declare this safe and read-only; the description adds valuable behavioral context beyond that: a hard cost of 1.00 USDC per call, roughly 80,000 rows for AWS, and that `regions` contains per-region as-of timestamps. This helps an agent anticipate cost and response size.

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?

Each sentence earns its place: cost is front-loaded, scope is explicit, and the relationship to /spot/snapshot plus output characteristics are stated in two compact sentences. No filler or redundancy.

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 one-parameter read-only tool with no output schema, the description gives enough context to invoke it correctly: scope, relationship to /spot/snapshot, rough result size, and `regions` semantics. It stops short of fully describing response fields, but the 'same rows as /spot/snapshot' reference covers that adequately.

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?

The schema already documents the sole `provider` parameter with a full enum and 100% coverage. The description mentions 'of a provider' and uses AWS as an example, but it does not add materially new parameter-level meaning beyond the schema.

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 resource (spot price snapshot), scope (every type, zone, and region of a provider), and differentiates from the related /spot/snapshot endpoint by noting it covers all regions in one call. The row-count detail reinforces the all-region scope.

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 'Same rows as /spot/snapshot, for all regions' provides context for when this tool is appropriate versus a more targeted snapshot. It does not explicitly say 'use spot_snapshot for single-region queries,' but the contrast is clear enough.

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