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

The annotations already establish read-only, idempotent, non-destructive behavior. The description adds substantial behavioral context beyond that: the 0.01 USDC per-call cost, the effective hourly USD calculation with amortized upfront, the change-point series structure, provider-specific data sources, refresh cadence, and history depth.

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 dense but every sentence earns its place: the paid nature and core scope are front-loaded, followed by AWS/Azure/GCP-specific facts. There is no fluff or repetition of schema content.

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 multi-provider, no-output-schema tool, the description is remarkably complete: it specifies cost, data sources, update frequency, history start dates, pricing computation, and scoping rules. The only mild ambiguity is the exact shape of a 'change-point series,' but that is not needed to select or invoke the tool correctly.

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 the baseline is 3. The description adds meaningful value by mapping ri_type values to providers, clarifying that instance names must match /instances exactly, and noting provider-specific region slug conventions. It does not fully explain every parameter, but the schema already carries precise descriptions.

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 defines the exact resource—reserved/reservation price history—and scopes it to a single instance type across AWS, Azure, and GCP with specific term types. It is unambiguous and clearly distinct from sibling tools like ondemand or spot_* by focusing on commitment-based pricing.

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 intended use is implied strongly by the name and content: use this when reserved or commitment-based price history is needed. However, the description never explicitly states when to prefer this tool over alternatives like reserved_snapshot or ondemand, and it gives no exclusions or conditional routing guidance.

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