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

With no annotations to lean on, the description fully carries the burden of behavioral disclosure. It reveals the output units (wei, gwei, native token cost), the multi-chain capability, the freshness limitation, and even the per-call cost of $0.005 USDC via x402 on Base. This is unusually transparent.

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?

Three sentences with zero waste: the first defines output, the second explains multi-chain usage, and the third covers timing and cost. Core information is front-loaded, and every sentence earns its place.

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 one optional parameter and no output schema, the description is complete. It explains the key return values (wei, gwei, transfer cost), the accepted inputs, the freshness caveat, and the monetary cost — everything an agent needs to select and invoke it correctly.

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 already provides 100% coverage of the single 'chain' parameter, including valid values, comma-separated format, examples, and default. The description adds a use-case nuance ('compare where to execute') but does not meaningfully expand 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 a specific action: providing live gas prices for five named chains and including a 21,000-gas transfer cost in the native token. This distinct focus on gas prices sets it apart from sibling tools like token_info or tx_status without ambiguity.

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 explicit timing guidance: 'Call this immediately before sending a transaction' and explains why ('gas moves every block, so the answer is good for seconds'). It also instructs how to compare chains with comma-separated values, which is practical usage guidance.

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