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

Beyond the readOnlyHint annotation, the description adds valuable behavioral details: results are cached for 10 seconds per chain, gas_used_ratio thresholds for congestion are defined, and optional USD estimates are explained. This gives the agent a comprehensive understanding of data freshness and interpretation, complementing the annotation.

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 three sentences, with the primary purpose front-loaded in the first sentence. Each sentence provides distinct value: purpose, core outputs and congestion interpretation, and optional extras/caching. No fluff or repetition, making it highly concise and well-structured.

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?

Given the tool's simplicity (two optional parameters, output schema present), the description is complete. It covers the purpose, key output fields, congestion thresholds, optional USD estimates, and caching. The agent has sufficient context to select and invoke the tool correctly without unmet informational needs.

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 already provides full descriptions for both parameters, achieving 100% coverage. The description adds minimal extra meaning, such as clarifying that USD estimates include rough transfer and swap costs. This is a baseline 3 where the schema does the heavy lifting, and the description offers marginal additional semantics.

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 gets current EIP-1559 gas fees on Ethereum or Base, with a specific verb and resource. It distinguishes itself from sibling tools like get_token_price or get_block by focusing on gas fees and listing specific outputs. The first sentence is explicit and unambiguous.

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 provides clear usage context: it is useful for timing transactions and network congestion assessment via gas_used_ratio. However, it lacks explicit alternatives or when-not-to-use guidance, though no sibling tool directly competes for this purpose. A 4 reflects strong context without explicit exclusions.

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