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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond that: the rate year (2026), the Toronto doubling effect, and buyer rebates. It does not describe the return format, but the annotations lower the burden enough that this is adequate.

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 sentences, front-loaded with a headline example that reads as marketing rather than functional guidance. The $700,000/$10,475 hook and the trailing URL consume space without helping an agent select or invoke the tool. It is compact but not every sentence earns its place.

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 7-parameter tool with no required params and no output schema, the description covers domain scope but omits what the calculation returns and how outputs are structured. The schema fully documents inputs, and annotations cover safety, so the gaps are moderate rather than severe.

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 baseline is 3. The description loosely connects to several parameters (Toronto doubling to the 'toronto' flag, provincial rates to 'region', rebates to 'firstTime'), but it adds no syntax, units, or conditional logic beyond what the schema already documents.

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 conveys that this computes land transfer tax for Canadian property purchases, with concrete scope details (2026 rates for every province, BC PTT, Quebec welcome tax, buyer rebates). It names no sibling, but the province-specific Canadian scope implicitly separates it from stamp_duty_calculator (UK) and dld_fee_calculator (Dubai). The purpose is delivered via example and scope rather than an explicit verb+resource statement, keeping it below a 5.

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?

There is no explicit when-to-use guidance and no alternatives are named. The agent must infer from the example (Ontario home) that this applies to Canadian real-estate purchases, and nothing tells it when to prefer this over canadian_mortgage_calculator or stamp_duty_calculator. Scope statements imply applicability but do not route usage.

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