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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds domain disambiguation: coins are valued at the day's price rather than indexed, amounts are in rial, and dates use the Jalali calendar. This is meaningful context beyond the annotations, though return format is not described.

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?

Two compact sentences, front-loaded with the core purpose before the usage directive and unit conventions. No filler, though the final clause about rial/Jalali slightly overlaps the schema.

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 computation tool with 7 parameters, one required, full schema coverage, and no output schema, the description supplies enough to understand both input modes and the units involved. The main gap is that it does not describe the shape of the returned valuation.

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 parameters are already well documented in the schema (including the coin-type enum and the estate/death-year nuance). The description only restates the rial/Jalali unit conventions, which is baseline-level added value.

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 (value) and resource (mehrieh) and explains the two valuation modes – indexed rial sum vs. gold coins at current price – which distinguishes it clearly from siblings like calculate_late_payment or calculate_stamp_duty.

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?

"Call it for any question about what a mehrieh is worth now, and never work the figure out yourself" gives a clear use condition and even an explicit directive against doing the math manually. It does not name alternative tools, but the applicability condition is unambiguous.

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