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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses the core formula and the output direction, but it leaves the n and inflation parameters unexplained, and it doesn't clarify the full output format. It also doesn't state whether there are any side effects, though as a calculation tool this is implied.

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 compact two-sentence definition that front-loads the formula and sibling distinction. There is no fluff or repetition. It's appropriately sized for the information it conveys.

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 tool has five parameters and no output schema or annotations, so the description must cover all inputs and expected outputs. It fails to explain the n and inflation parameters and gives only a cryptic 'Returns direction=deflate' without describing the actual return structure. This makes the definition incomplete for confident correct invocation.

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 schema descriptions are generic placeholders ('N to process'), so the description is the only source of parameter meaning. It clarifies value, rate, and years through the formula, but n and inflation remain unclear, so an agent may not know how to populate them. This partially compensates for the schema's lack of semantic content.

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 deflates a future nominal amount to today's purchasing power using the formula value / (1+rate)^years. It explicitly distinguishes itself from x402-inflation-adjust by labeling itself the opposite. This gives an agent a precise understanding of the tool's purpose and how it differs from its sibling.

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 names the sibling tool x402-inflation-adjust and identifies this tool as its opposite, providing a clear when-to-use versus when-not-to-use signal. However, it doesn't go beyond that to discuss other alternatives like purchasing-power tools, but for the main scenario it is sufficient. It could be improved by explicitly stating 'Use this when you need to convert future amounts to present value.'

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