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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds useful behavioral context: it returns dollar savings at the current DPX all-in rate (~2.035%) and includes GENIUS Act and MiCA compliance status for each competitor. No contradictions with 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 concise and front-loaded, immediately listing competitors and rates, then shift to return behavior. Every sentence provides concrete, actionable information without redundancy or 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?

The description covers the comparison scope, competitor list, output details (savings and compliance), and the current DPX rate. An output schema exists, so return structure is already documented. A minor gap is that optional parameters like esgScore and hasFx are not explained in the description, but the schema covers their semantics.

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 input schema covers all three parameters with descriptions (100% coverage), so the description doesn't need to compensate. The description adds no parameter-specific meaning beyond what the schema provides, which is acceptable given high schema coverage.

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 states the tool's function: comparing DPX settlement costs against a specific list of competitors (Stripe, Wise, Ripple, etc.) and returning savings plus compliance status. This distinguishes it from sibling tools like fees.schedule and fees.verify, which likely handle schedule-only or verification-only concerns.

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 provides clear context for when to use the tool: when a comparison of DPX fees to competitors is needed, with specific competitor rates included. It doesn't explicitly name alternatives or exclusion criteria, but the detailed competitor list makes the use case obvious.

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