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

Annotations already establish a safe read-only, idempotent operation. The description adds useful context beyond those hints: it lists return fields, explains that omitted choices fall back to calculator defaults, notes that the result exposes changeable choices, and confirms nothing is saved or ordered. It stops short of error or rate-limit behavior.

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 three tight sentences: it front-loads the action and return payload, then adds default and persistence notes. Every sentence adds distinct information with no 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?

With no output schema, the description carries the burden of explaining return values and does so thoroughly, listing the material fields, VAT breakdown, and matching products. Combined with complete parameter documentation and annotations covering safety, the agent has everything needed to invoke it 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 meaning for the choices parameter—omitted choices use defaults and the result lists changeable choices—and contextualizes the calculator parameter as 'one of the website calculators', going beyond the schema's raw 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 states a specific verb ('Runs one of the website calculators') and resource ('material list'), and the action is clearly distinct from sibling tools like list_calculators and search_products. An agent can immediately tell this tool performs a calculation rather than listing or searching.

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 description implies usage by explaining it runs a calculator for an area and returns materials, but it never names alternative tools or states when to prefer this over list_calculators or search_products. The note that nothing is saved or ordered gives a mild exclusion but no explicit when-to-use routing.

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