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

Annotations declare readOnlyHint=true, and the description does not contradict this. The description adds behavioral context beyond annotations by detailing the specific cost components included (transfer tax, municipal fees, etc.) and mentioning optional mortgage costs, which is useful for understanding the tool's scope.

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 a single sentence that efficiently conveys the core purpose and usage. It is front-loaded with the primary function and uses a comma-separated list for clarity. No wasted words.

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?

Given no output schema, the description does not explain return values. However, it lists the cost components, giving a good idea of what will be returned. It is mostly complete for a calculation tool, but could specify whether it returns a total or breakdown.

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 description coverage is 100%, so the input schema already documents all three parameters. The description adds no new parameter-level details, just reinforces that mortgage costs are optional. Baseline of 3 is appropriate.

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 tool's purpose: providing an official closing-costs breakdown for buying property in Paraguay, listing specific fees (transfer tax, municipal fees, etc.). It uses a specific verb 'breakdown' and resource 'closing-costs', and distinguishes from sibling tools by specifying the country and context.

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 explicitly says when to use the tool ('when the user asks what buying costs beyond the price, or to budget cash-at-closing for a concrete price'). It provides clear usage context but does not mention when not to use or list specific alternative tools.

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