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

The description adds 'deterministic calculations' and 'Calculation only,' reinforcing the read-only and idempotent nature already indicated by annotations. It does not reveal additional side effects or error behaviors, but the added emphasis on no side effects provides some extra transparency.

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 concise, two sentences, with no fluff. It efficiently states the purpose and then usage constraints, making it easy to parse and understand.

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 the tool's clear scope and the presence of an output schema (per context), the description adequately covers the main aspects: what it does, limits, and constraints. It does not explain return values, but the output schema handles that. Some details about error handling or edge cases are omitted, but the description is sufficient for a calculation-focused tool.

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 67% (jurisdiction and effectiveDate have descriptions; scenarios itself lacks one but its nested fields are described). The description adds no specific parameter details beyond stating inputs should be 'explicit, non-identifying numeric inputs,' which is generic and does not enhance the schema's own 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 clearly states the tool's purpose: 'Compare up to six Canadian fixed-rate payment and amortization scenarios using deterministic calculations.' It specifies the resource (mortgage scenarios), action (compare), and constraints (Canadian, fixed-rate, up to six), distinguishing it from sibling tools that focus on individual calculations.

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 provides usage boundaries: 'Use only with explicit, non-identifying numeric inputs' and explicitly states when not to use it ('never use this tool to approve, deny, underwrite, recommend...'). It lacks explicit references to alternative tools, but the purpose is clear enough to guide selection.

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