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

With no annotations, the description must carry the behavioral load. It does disclose the useful commercial/auth detail that calls are metered ('5 free trial calls per signed wallet'), which tells the agent a wallet signature is involved, but says nothing about data freshness, sources, rate limits after the trial, or failure behavior.

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 compact segments with the core capability front-loaded and the trial note clearly secondary. Nothing is wasted, though the emoji adds little informational value.

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 tool with two entirely undocumented string parameters, no output schema, and no annotations, the description leaves too much unstated — input format and expected response shape are both unknown. The payment/trial note is the only substantive behavioral detail provided.

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 0% — both 'labels' and 'tokens' are bare strings with no descriptions, types beyond string, or examples. The description does not explain whether tokens are symbols or addresses, how multiple tokens are delimited, or what 'labels' maps to, so the agent cannot reliably construct a valid call.

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?

Names a specific verb ('compare') and resource ('token price/liquidity/volume') with a clear 'side-by-side' scope, which separates it from single-asset siblings like x402-token-price or x402-token-market. It does not name those siblings directly, so the differentiation is implicit rather than stated.

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 'side-by-side' framing implies multi-token usage, and the trial note sets context for first use, but there is no explicit when-to-use/when-not guidance and no pointer to the sibling tools for single-token lookups. The agent must infer the boundary from the name alone.

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