Key rates summary

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered; the bar is lower. The description adds genuinely new behavioral context by defining unit conventions (*_toman for rial figures, USD for ounce, Brent, Bitcoin and Ethereum), which prevents unit misreads. It does not note data freshness/latency or update cadence, which would matter for a 'today's rates' tool.

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?

Front-loaded with the capability, then the usage rule, then the routing hint — a sensible order with no filler. The long instrument enumeration is slightly list-heavy, though it earns its place by signalling scope.

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?

With no output schema, the description partially compensates by naming the returned instrument groups and clarifying units, which is the key ambiguity for this tool. It stops short of describing the response structure (grouping, ordering, timestamp), which is the remaining gap.

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 tool takes zero parameters, so the baseline is 4. The schema is trivially complete and the description correctly spends no space inventing parameter semantics.

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?

Concrete verb-and-resource framing ('Key Iranian market rates in one call') followed by an explicit enumeration of what is returned: dollar, euro, dirham, gold gram/ounce, coins, silver, Brent, Bitcoin, Ethereum, Tether. It also names the drill-down sibling tj_category_table, so an agent can distinguish it from the other price tools.

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 first for what are today's rates' is an explicit default-selection rule, and 'Drill into a group with tj_category_table' names the alternative and the condition that routes to it. Nothing about when to pick this over its siblings is left to inference.

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