compare_modes

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

No annotations exist, so the description carries the full burden. It does disclose output content ('cost per mode and the saving vs on-demand') and that modes are ondemand/monthly/yearly, which is valuable since there is no output schema. It omits that this is a non-mutating calculation and says nothing about whether region/currency affect which prices are used.

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?

Three short lines, front-loaded with the core action, followed by item format, return values, and valid modes. No filler, though the backtick/newline formatting makes it slightly clipped.

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?

With no annotations and no output schema, the description must explain both behavior and returns. It covers the return content at a high level but not its structure (e.g., keys per mode, currency of the saving), and gives no guidance on how region/currency interact with the comparison.

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%, so the description must compensate. It documents the `items` element shape ([{service, spec, quantity, size, usage_*}]) and enumerates the mode strings, but leaves `region` and `currency` unexplained beyond their schema defaults — their accepted formats and effect on results are unstated.

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?

States a specific verb (compare) and resource (bill of materials across billing modes), plus what is returned. It implicitly differentiates from sibling compare_regions by scoping to modes, though it never names that sibling.

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?

Usage is implied: use it to evaluate the same BOM under ondemand/monthly/yearly pricing. There is no explicit when-to-use guidance, no prerequisites (e.g., do you need auth or a price list first), and no named alternative such as compare_regions.

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