Currency, gold, coin and commodity prices

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

Annotations already declare this a safe, idempotent read, and the description builds on that with real operational context: single source ('Mofid only'), unit conventions ('Rial prices: divide by 10 for Toman'), the fields each row carries in live vs history mode, ordering ('oldest first'), and coverage horizon ('back to 2019-2021'). This is information an agent cannot recover from the annotations or schema.

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 resource list and the live/history split, then a compact source-and-shape paragraph. Dense but every sentence carries signal; the trailing sibling reference sits awkwardly at the end of a paragraph about row formats rather than in its own routing sentence.

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 and four optional parameters, the description does the heavy lifting: it names the row fields, ordering, unit system and data source. What is missing is failure behavior, e.g. what happens when no code matches or when history is requested for a range beyond the available window.

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 100%, so the baseline would be 3; the description earns more by explaining that history mode requires an exact code and by clarifying the unit basis behind currency/gold_coin versus commodity values. It does not add much beyond the schema's own per-parameter descriptions, so it stops short of 5.

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?

Opens with a specific verb and resource set ('Return free-market prices of currencies, crypto, coins, 18k gold, the global ounce, oil and metals') and adds the distinct history mode ('or one code's daily history'). The two modes are cleanly separated, so an agent can tell this apart from quote/screener siblings without opening the schema.

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?

Explicitly names the alternative for a quick glance ('Agah's br_market also shows dollar, coin, gold and oil prices'), which steers agents away from this tool when they only need a top-level view. It also implies the history branch requires an exact code, though it never states a hard when-not condition such as 'do not use for equities or funds'.

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