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

The annotations already declare this as read-only and idempotent, and the description is consistent with that. Beyond the annotations, the description adds useful behavioral context: it explains the realValue and equivalentNeeded outputs and provides a numeric example that implies the compounding formula used. This helps the agent understand expected results without contradicting any annotation.

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 two sentences: a concise statement of behavior followed by a compact illustrative example. It is front-loaded with the key verb and outcome, and every part earns its place without fluff or repetition.

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 that an output schema exists, annotations cover safety/idempotency, and the input schema documents all parameters with defaults and constraints, the description supplies the missing conceptual meaning through the example. An agent has everything needed to invoke the tool correctly and interpret its outputs.

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 goes beyond the schema by giving a concrete example that maps amount=100000, rate=3, and years=10 to specific outputs, reinforcing what each parameter means and how they relate. It does not add new details about the lang parameter, but the schema already handles that.

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 opens with a specific verb ('Calculate') and clearly identifies both the resource (cash purchasing power) and the two outputs (lost purchasing power and nominal amount needed to preserve buying power). The example with concrete values (realValue ≈ 74,409, equivalentNeeded ≈ 134,392) makes the tool's purpose unmistakable and distinguishes it from calculator siblings like compound_interest or compare_investments.

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 purpose is clear enough that an agent can infer when to use it — when converting today's cash into future purchasing power under inflation. However, there is no explicit guidance about when not to use it, no mention of alternatives such as compound_interest for growth calculations, and no stated prerequisites or assumptions.

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