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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint, but the description adds a materially useful detail the annotations cannot express: a pay-per-call cost of $0.005 USDC via x402. It reinforces that no signing/wallet access occurs, which is redundant with but clearer than a bare readOnlyHint.

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 short clauses, front-loaded with the purpose and immediately followed by unit of return, safety profile, and cost. No filler or restatement of the tool name.

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?

There is no output schema, and the description compensates by specifying the return value and unit ('balance in wei'). Combined with the disclosed payment requirement and read-only guarantee, an agent has everything needed to call this 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?

Schema coverage is 100%, so the single address parameter and its 0x-prefixed 20-byte pattern are fully documented in the schema. The description only implies the address via 'a Base wallet' and adds nothing about chain targeting or address format, so baseline 3 applies.

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 (check/return), resource (native ETH balance of a Base wallet), and unit (wei). The qualifier 'native ETH' implicitly separates it from the sibling base_erc20_balance, so an agent can route without opening either schema.

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 phrase 'available for gas' hints at the intended use case (pre-flight gas sufficiency check), but the description never states when to prefer this over base_wallet_snapshot, base_eth_call, or base_erc20_balance, nor any precondition beyond a valid address.

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