get_exchange_rate

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

With no annotations provided, the description carries the full burden, and it delivers: it discloses the return shape as a JSON object with rate/source/target/time, the semantic meaning (1 source = X target), and the important behavioral limitation that crypto, commodities, and arithmetic are not supported. This goes well beyond a basic restatement.

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 compact and front-loaded with usage triggers, then the return format, then exclusions, then sibling routing. Every sentence adds distinct value, and there is no redundant filler.

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 two-parameter tool with no output schema, the description is complete: it explains when to use it, what the output looks like, what it explicitly cannot do, and which sibling tools cover adjacent cases. An agent has everything needed to call it correctly.

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%, and both source and target parameters already have detailed schema descriptions including ISO 4217 format, case, examples, rate-direction semantics, fiat-only constraint, and a pointer to list_currencies. The tool description repeats the rate direction but adds little that is not already in the schema, so a baseline 3 is appropriate.

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 names the exact operation: returning the latest mid-market rate for a single fiat-to-fiat pair. It gives concrete user phrasings and explicitly distinguishes itself from sibling tools like get_rates and get_historical_rates. Nothing about the tool's core purpose is ambiguous.

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 states clear when-to-use conditions ('single fiat-to-fiat live exchange rate question'), explicit exclusions (crypto, commodities, arithmetic), and direct alternatives (get_rates for multiple targets, get_historical_rates for past dates/lookbacks). This gives an agent strong routing guidance.

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