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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description goes further by disclosing the commitment models priced, the break-even-hours output, and the cheapest-region fallback behavior — real context beyond the annotations, though it says nothing about pricing freshness or rate limits.

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 tightly packed sentences with the core output (costs plus break-even) front-loaded and the usage hint last. No filler, no restatement of the title.

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 an output schema present, return-format details are unnecessary, and the annotations carry the safety profile. The description covers what is computed and how it can be used; only the routing relative to sibling pricing/lookup tools is left implicit.

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 every parameter including defaults (linux, 730 hours, 1 instance) is already documented in the schema. The description adds only the loose hint of comparing sizes or regions, which does not meaningfully extend the parameter definitions.

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 states a specific computed output (monthly and yearly cost for one or more Azure VM sizes) plus the pricing models covered (pay-as-you-go, reservations, savings plans) and the break-even metric. This distinguishes it from the lookup-oriented siblings find_vm_sizes and get_vm_size, though it never names them explicitly.

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?

"Use it to compare sizes or regions" gives an implied usage scenario but offers no when-not-to-use guidance or explicit routing to find_vm_sizes / get_vm_size / get_price_changes. An agent can infer the fit, but nothing is stated about exclusions or prerequisites.

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