Convert an amount between currencies using free, keyless public FX rates (Frankfurter/ECB), fetched on demand. Returns the rate and converted amount. Read-only; price 0.0 (free).
| Name | Required | Description | Default |
|---|---|---|---|
| to | Yes | Target ISO 4217 currency code | |
| from | Yes | Source ISO 4217 currency code | |
| amount | Yes | Amount to convert |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the burden of disclosing behavioral traits. It explicitly states that the tool is read-only, has zero cost, and fetches rates on demand from Frankfurter/ECB, which is valuable context. It does not mention error conditions or rate freshness, but the core safety and cost profile are covered.
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 description is efficiently written in three short sentences, each adding distinct value: the conversion action and rate source, the return values, and the read-only/free status. There is no redundant or extraneous information, making it highly concise and front-loaded.
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 converter with three parameters and no output schema, the description provides sufficient context: it explains the action, the data source, the return payload, and the cost/safety profile. It does not enumerate supported currencies or rate update frequency, but these are not essential for basic invocation, making it almost complete.
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 input schema already provides 100% descriptive coverage for all three parameters (amount, from, to), so the description does not need to repeat them. However, it does not add any extra meaning beyond the schema, such as examples, constraints, or the relationship between parameters, so it stays at the baseline.
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?
The description clearly states the tool's function with a specific verb ('Convert') and resource ('currencies using free, keyless public FX rates'), and it names the source (Frankfurter/ECB). It also specifies the return values (rate and converted amount), making it distinct from sibling tools like fx_tax_sales_tax or price_oracle_convert. This fully clarifies its purpose.
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?
The description implies usage for currency conversions needing free, keyless FX rates, but it does not explicitly mention alternatives or exclusions. It offers no guidance on when to use this tool versus similar ones like price_oracle_convert or fx_tax_list_rates, so the agent must infer suitability from the 'free, keyless' wording.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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Every tool follows a consistent `domain_subdomain_action` pattern with underscores, e.g., `agent_audit_query`, `bid_watch_search`. Even long names like `commerce_catalog_agent_readiness_score` adhere to this structure.
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