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

With no annotations, the description carries the full behavioral burden, and it does disclose the important non-obvious trait: the tool is pay-per-call at 0.01 USDC on Base via x402, 12 sats Cashu ecash, or 12 sats over Lightning (L402). It also enumerates the returned fields. It does not mention rate limits, caching/freshness guarantees, or error behavior, so it falls short of full disclosure.

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 sentences, both front-loaded with the most decision-relevant information (what it returns, then what it costs). No filler, no restatement of the name or title.

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 one-parameter, no-annotation, no-output-schema tool, the description supplies the return fields, the chain selection semantics, and the payment model — enough for an agent to call it correctly. Gaps remain around error handling, rate limits, and freshness, but the core is covered.

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 schema documents the single 'chain' parameter with 0% description coverage and no enum, so the description must compensate. It does: it lists the accepted chain names and explains that omitting 'chain' returns all chains while 'chain=' selects one, adding real semantics beyond the bare string type.

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 ('Live gas snapshot across EVM chains in one call') and enumerates the covered chains, making it immediately distinguishable from siblings like evm_balance, evm_token, and evm_tx. The scope and output content are stated up front.

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 '(ethereum, base, arbitrum, optimism, polygon, or chain= for one)' implies the two usage modes — omit chain for all, pass chain for one — but the guidance is embedded rather than explicit. There is no statement of when to prefer this tool over evm_balance/evm_tx, and no exclusions or prerequisites beyond the payment note.

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