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

With no annotations, the description carries the full behavioral burden and does disclose genuinely useful context: a fixed price of $0.0050 USDC per call, the x402 payment requirement, the POST endpoint, the upstream source and its fallback, and that data is live. It stops short of covering rate limits, error/failure behavior, or whether calls are cached, so it is strong but not exhaustive.

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 purpose is front-loaded and the '||' separator keeps sections scannable, which is good. However, the literal POST URL and the partial restatement of the input parameters duplicate what the runtime and schema already convey, so not every sentence earns its place.

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 two-parameter, annotation-free, output-schema-free tool, the description supplies the essentials an agent needs: what it returns (live FX rates, MYR inclusive), the cost model, the transport, and the input contract. The main gap is that no output schema exists and the description does not sketch the response shape (e.g. rate fields per target currency), which would help an agent parse results.

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 both parameters are already documented in structured form, including the comma-separated format and the default target set. The description merely restates 'dari' (base code) and 'ke' (comma-separated targets) without adding format, constraint, or edge-case detail beyond the schema. Baseline 3 applies.

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 concrete purpose: current currency exchange rates, names the data sources (open.er-api.com with ECB Frankfurter fallback) and the MYR coverage, and sketches the input shape. It is clearly distinguishable from data-processing siblings like json or terjemah, but it never names or contrasts with near-neighbours such as harga or quote, so sibling differentiation is left implicit.

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?

There is no statement of when to choose this tool over alternatives (harga, quote, banding-token), no exclusions, and no preconditions beyond the input format. The only usage-adjacent content is the parameter syntax, which duplicates the schema rather than guiding selection.

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