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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds non-obvious context that these are reference prices that may diverge from live paywall amounts, which is exactly the kind of semantic caveat annotations cannot express. It does not describe the return shape, but annotations carry most of the burden.

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?

A single sentence that front-loads the core action and folds the caveat into a compact parenthetical. Every clause earns its place with no padding.

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?

For a zero-parameter, non-destructive read with no output schema, the description covers purpose and the key semantic caveat about reference vs live prices. It could add a note on whether the list is global or scoped, but nothing essential to invoking it correctly is missing.

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 tool takes zero parameters, so the baseline is 4 and there is nothing for the description to clarify or omit. No parameter-level confusion is possible.

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+resource: 'Get public x402 list prices for lookup and scores.' That is clearly distinct from data-oriented siblings like connect_lookup, connect_scores_batch, and connect_trust_graph. It stops short of a 5 because 'x402' is domain jargon an agent may not resolve, and no sibling is named for contrast.

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 parenthetical 'reference only; live paywall amounts are in 402 responses' gives real routing guidance: use this for list/reference pricing, not for live paywall amounts. It stops short of a 5 because it does not name the alternative tool or endpoint that supplies live amounts.

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