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

With no annotations, the description is fully responsible for behavioral disclosure. It only states the core action ('compare live gas... find cheapest') but does not reveal whether the operation is read-only, how the data is obtained, whether there are rate limits, or what the output shape is. The word 'live' adds a minimal real-time signal, but the description falls short of the transparency expected without annotations.

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 very short and efficiently structured, with the purpose front-loaded in a title and a single explanatory sentence. Every part ('multi-chain', 'compare live gas', 'find cheapest') adds useful context, and there is no filler.

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?

The tool has no output schema and no annotations, and its two parameters are optional and vaguely described. The description fails to explain how to supply chains, what the output will be (e.g., list of chains with gas prices vs. just the cheapest), and what 'cheapest' refers to (native gas fee vs. USD-equivalent). An agent would be uncertain how to invoke the tool correctly in many scenarios.

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 input schema has 100% description coverage with generic entries ('Chain to process' and 'Chains to process'), so the baseline is 3. The tool description does not clarify the relationship between the singular and plural parameters, what values are accepted (e.g., chain names or IDs), or how to specify chains for comparison. Thus the description adds no meaningful parameter semantics beyond the schema.

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 clearly states the tool's function: comparing live gas across chains and finding the cheapest. This is a specific verb ('compare') plus resource ('live gas across chains'), and the 'multi-chain' qualifier distinguishes it from single-chain gas tools among the siblings, even though it doesn't explicitly name alternatives.

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 description gives a clear context for when to use the tool: when the user needs a multi-chain gas comparison, especially to find the cheapest chain. However, it does not provide explicit when-not-to-use guidance or mention alternative tools like x402-multi-gas or x402-gas-price, which are present among the siblings.

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