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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false. The description adds useful behavioral context by framing this as a single aggregated call that computes multiple derived metrics in one response, which goes beyond the safety annotations.

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 the resource and purpose. The colon-separated list is dense but informative; 'Decision-grade' is somewhat rhetorical, but the rest of the text 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?

With no output schema, the description carries the burden of explaining return content, and it does enumerate the main output components. It does not define terms like 'verdict' or describe return structure, but the simple two-parameter input and strong annotations reduce the need for more detail.

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%, with base and quote already described as three-letter currency codes. The description reinforces that the tool operates on a single pair but adds no additional format, validation, or usage detail 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?

The description clearly identifies the resource ('one currency pair') and enumerates the specific outputs: latest rate, 30/90-day volatility, trend, anomaly z-score, spread estimate, cross-strength, and verdict. This differentiates it from most sibling FX tools like fx_rates or fx_strength, though no sibling is explicitly named.

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 phrase 'Decision-grade single-call summary' implies use when a consolidated, multi-metric FX profile is needed, and 'one currency pair' indicates scope. However, it does not explicitly state when to prefer this over fx_strength, fx_timeseries, or fx_convert, nor does it provide exclusions.

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