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

With no annotations, the description must carry the behavioral burden. It does add one notable behavior—'Price 0.01 via x402 (USDC on Base)' suggests a payment/credit requirement—but it is phrased as 'd Price 0.01' and is unclear. It doesn't disclose whether this is a read-only computation, how often data updates, or what 'raw series' means.

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 short and front-loaded, but the run-on sentence contains a truncated, nonsensical segment ('into d Price 0.01 via x402') that appears to be a formatting error. The text does not read as professionally structured.

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?

No output schema exists, so the description should explain what the agent will receive; it lists three signal components, but leaves the instrument ('Nordic ECB FX'), the meaning of the percentile/momentum/verdict, and the payment/credit workflow unclear. For a tool with one optional parameter it is not unusable, but it is not complete enough for confident invocation.

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 only parameter, wallet, is fully documented in the schema (100% coverage), including free-tier credit details. With the schema shouldering the explanation, the description adds no needed parameter semantics, so the baseline of 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?

Description names a specific verb and resource: 'get live computed signal' for a 'Processed analytics layer over FX', and lists concrete outputs (30-period percentile rank, 4-period momentum, trend verdict). However, it doesn't differentiate from the many FX siblings like processed_fx_rates or processed_no_fx_latest, and the garbled 'into d Price 0.01 via x402' undermines precision.

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 guidance about when to use this tool instead of alternatives such as processed_fx_rates, processed_fx_hist, or the signal_* tools. The description only states what the tool computes, leaving selection entirely to inference from the sibling names.

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