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

Beyond the annotations (readOnlyHint, idempotentHint, destructiveHint), the description explicitly states it does not change page or account state, access customer data, or give personalized advice. These added behavioral guarantees provide value beyond the structured annotations and fully disclose operational boundaries.

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 with zero wasted words. It front-loads the read-only educational nature, then the core function, and ends with safety clarifications. 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?

The description covers the core calculation and safety behavior, and the output schema exists, so return values need no description. However, it omits the optional categoryRates parameter, which is documented in the schema. This is a minor gap, but an agent relying solely on the tool description might miss this advanced feature. Overall, adequate for basic usage.

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?

The input schema alone provides 100% coverage with detailed descriptions for all four parameters, including categoryRates which is described as an optional override. The tool description mentions only amount, years, and inflation rate, omitting categoryRates entirely. Thus it adds minimal semantic value beyond the schema, earning the baseline score for high schema coverage.

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 projects purchasing power erosion from amount, years, and inflation rate, which is a specific and distinct calculation. While it does not explicitly name alternatives, the domain (inflation) is evident from the name and the calculation description, making it distinguishable from sibling calculators without further elaboration.

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 clear context: it is a read-only educational calculator for projecting purchasing power erosion. It implicitly indicates when to use the tool (for inflation-related projections) but does not mention alternatives or exclusions. This meets the 'clear context, no exclusions' bar.

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