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

Annotations only declare readOnlyHint, but the description adds substantial behavioral context beyond that: the exact cost ($0.01 USDC per call), the payment rail (USDC on Solana mainnet), and the challenge/retry auth handshake. This is precisely the auth-and-cost disclosure the annotations cannot carry.

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 tight sentences: the first front-loads what is returned and the price, the second lays out the payment sequence. No filler, and the ordering matches how an agent must act.

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 must imply the return shape; 'all four tracked stablecoin pegs' conveys coverage but not what fields come back per peg (price, deviation, timestamp). Everything needed to invoke it correctly, including payment, is present.

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% and the sole parameter's schema description already explains the omit-then-retry flow, so the description largely restates it. Baseline 3 applies since the schema does the heavy lifting and the description adds no syntax or format detail beyond it.

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 ('all four tracked stablecoin pegs') and enumerates exactly which pegs (usdt, usdc, usde, dai) are returned in one call. This clearly separates it from the sibling get_peg, which presumably returns a single peg.

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?

Gives an explicit two-step invocation flow: call without payment_signature to get the challenge, pay USDC on Solana, then call again with the signature. It does not, however, say when to prefer this batch call over the single-peg get_peg sibling, leaving that choice to inference.

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