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

With no annotations provided, the description carries the full behavioral burden. It discloses a genuinely useful constraint — '🆓 5 free trial calls per signed wallet' — signaling auth requirements and metered usage. But it stops there: no mention of read-only behavior, post-trial behavior, supported chains, or response characteristics.

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 only 12 words and front-loads the purpose, which is efficient. But 'Price Oracle: Multi-source price oracle' repeats 'price oracle' twice given the tool name already states it, and the useful quota information is tucked into an emoji-laden aside.

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 six optional parameters, no annotations, and no output schema, the description leaves major gaps: which parameters are interchangeable selectors, which chains/networks are supported, what the response includes, and how this oracle differs from its price siblings. Only the free-trial and multi-source notes carry substance.

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%, so the baseline is 3. However, every schema description is a placeholder ('Chain to process', 'Token to process') that merely repeats the parameter name without format or selection guidance. The tool description adds nothing about how chain/network/address/symbol/ticker relate, leaving the agent to guess which parameter to supply.

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 conveys a resource (price data) and a distinguishing trait ('Multi-source price oracle'). However, 'Price Oracle: ... price oracle' largely restates the tool name, and it does not specify asset scope (crypto/fiat/stocks) or differentiate from the many price siblings in the list such as x402-crypto-price, x402-token-price, and x402-dex-price.

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 about when to use this tool versus the numerous price siblings (x402-crypto-price, x402-token-price, x402-dex-price, x402-stock-price, x402-currency-rate). The only usage-adjacent note is the free-trial quota, which concerns cost, not tool selection.

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