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

Beyond annotations (readOnly, openWorld, idempotent, non-destructive), the description adds substantial behavioral detail: returns both units, optional fields (base fee, priority fee, block number) dependent on node availability, three-node fallback, keyless access, and the exact cost of 0.001 USDC per call via x402. These are meaningful operational facts that affect how an agent plans and budgets the call.

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 front-loaded with the essential payload, then gives a brief rationale for dual units, followed by infrastructure and cost. Each sentence contributes distinct value – no filler. The length is justified by the need to communicate fallback behavior and metering.

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 parameterless tool with a rich output schema, the description covers all relevant non-schema information: chain, units, optional fields, source reliability, keyless nature, and cost. The output schema handles return-value details, so nothing an agent needs to decide whether to call this tool and what to expect is missing.

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 tool has zero parameters)Skip, so the schema is trivially fully covered and there is nothing to document. Per the baseline for 0 params, a score of 4 is appropriate; the description adds no parameter semantics because none are needed.

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 identifies the resource (Base gas price on chain 8453) and specifies the returned fields (gwei, wei, base fee, priority fee, block number). It does not explicitly name a sibling tool to distinguish from, but the chain ID and unit duality make its purpose concrete. A 5 would require an explicit sibling contrast such as 'use get_priority_fees for priority fee breakdowns.'

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 clear context for when to use the tool: when needing base gas price in either gwei or wei. It explicitly explains that both units are returned because they are the same question, discouraging redundant calls for the other unit. It also provides operational context (keyless RPC, no key rotation, cost per call) but does not mention alternative tools or exclusion conditions, so it falls short of a 5.

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