Signed reference rates, always as-of stamped (PAID $0.01)

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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior. The description adds important context beyond annotations: the exact payment cost and rail (0.01 USD x402 on Base/USDC) and the signed/as-of guarantee.

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-loads the key facts. It is slightly redundant because the title text is repeated verbatim, and the remote-route line is terse but sufficient.

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?

An output schema exists, so return values need not be described. However, for a rates tool, the description does not clarify what base/quote/symbol mean or what happens with no parameters, leaving the calling semantics underspecified despite rich annotations and a full output schema.

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 the baseline is 3 even though the schema descriptions are minimal. The description does not add any meaning for base, quote, or symbol beyond what the schema already provides.

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 states the specific resource (reference rates) and its key property (signed, as-of stamped), and gives the HTTP route. It does not, however, differentiate against similar siblings such as v1_market_snapshot or v1_nav_attest.

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 on when to use this tool versus alternatives. The description only states that the endpoint is paid and gives the payment rail, not the scenarios that should select it.

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