FX Rates

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

Annotations already declare readOnly, idempotent, non-destructive, and open-world behavior, so the safety profile is covered. The description adds genuine value beyond that by disclosing the data source (ECB reference rates), which tells the agent about provenance and update cadence. It stops short of stating freshness or rate limits.

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 tightly written sentences, front-loaded with the core action and following with the optional narrowing and data source. No filler or 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?

For a simple zero-required-parameter read tool with a full schema and an output schema (so return values need not be explained), the description covers purpose, default, filter, and source adequately. Only the absence of routing guidance against the four siblings keeps it from being fully 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?

Schema description coverage is 100%, so both parameters (base, symbols) are fully documented in the schema, including the USD default and comma-separated format. The description restates the same defaults and target-currency concept without adding syntax or constraints beyond the schema.

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 and resource ('Get the latest foreign-exchange rates') plus scope (base currency, optional targets). 'Latest' implicitly distinguishes it from fx_historical/fx_timeseries, but no sibling is named explicitly, so differentiation is inferred rather than stated.

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?

Usage is implied by 'latest' spot rates and the optional target filter, which contrasts with time-series siblings, but the description never states when to choose this over fx_convert, fx_historical, or fx_timeseries. No explicit alternatives or exclusions are given.

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