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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: quote units may be per 10 or 100 units (critical for interpreting later rate calls) and Pro-only currencies appear with pro_only=true. It does not say whether Pro-only entries are always present or how many currencies there are.

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 sentences, front-loaded with the scope and field list, with no filler. The Persian sentence mirrors the English rather than adding new information, which is reasonable for a bilingual board but is mild redundancy.

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 parameters and no output schema, the description carries the return-value burden and does so by enumerating the fields plus the pro_only flag. Missing minor items such as ordering or whether the list is exhaustive of the board, but an agent has everything needed to call and interpret it.

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 no parameters, so the baseline is 4. The description instead documents the return shape (fields and the pro_only flag), which is more useful here than parameter detail would be.

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 (list) and a precisely scoped resource (every currency on the NetArz Tehran free-market board), and names the returned fields: ISO code, Persian/English name, quote unit, page URL. It does not explicitly contrast with siblings like get_rate or convert, but the catalog-enumeration purpose is unmistakable.

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?

No explicit when-to-use or when-not-to-use statement, and no sibling is named. Usage is only implied: an agent can infer this is the discovery step that yields currency codes for get_rate/convert, but the description never says so.

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