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

With no annotations, the description carries the full burden. It discloses the return value ("Returns the converted amount") and a cost model ($0.003 per call, USDC on Base), which is useful. However, it never explains how conversion direction is determined or what happens on invalid input/units, leaving meaningful behavioral gaps.

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 conversion rule is front-loaded in the first clause, followed by usage context, return value, and cost. Four short sentences with little waste; the pricing parenthetical is slightly tangential but informative for an agent.

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 simple two-way conversion the core concept is well covered, and no output schema means return values needn't be detailed. But with 0% parameter coverage and an unexplained `number` parameter, the description is not complete enough to guarantee a 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?

Schema coverage is 0% for three parameters (amount, unit, number), so the description must compensate. It explains the conversion concept and rate but never clarifies the `unit` values or what the mysterious `number` parameter means, leaving the parameter semantics largely undocumented.

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?

States a specific verb (convert) and resource (amount between Iranian rial and toman) and pins the exact rate (1 toman = 10 rial). No sibling tool performs currency conversion, so differentiation is inherent, and the agent immediately knows what this does.

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?

"Use it when a price is given in one unit and must be shown or billed in the other" gives clear when-to-use context. There are no relevant alternative tools to name and no exclusions or prerequisites are stated, so it stops just short of the top band.

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