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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly says 'Read', which implies a non-destructive, read-only operation, and it discloses the cost ($0.003 USDC via x402). This adds value beyond the schema. However, it does not describe the response format, what happens on invalid input or errors, whether the balance is returned in wei or ETH, or any rate limits or caching behavior. For a simple read tool, this is adequate but not thorough.

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 two sentences, with the core purpose front-loaded and the cost information as an important secondary detail. Every word earns its place; there is no padding or redundancy. This is exemplary conciseness for a tool with a single parameter.

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 of this simplicity (one parameter, no output schema), the description is mostly complete in stating what it does. However, it fails to specify the return value format (e.g., balance in wei vs ETH, decimal precision), which an agent would need to correctly interpret the result. It also does not mention any edge cases like zero balance or invalid address handling. Since there is no output schema, this gap is more significant, making the description only partially complete.

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 description coverage is 0%, so the description must compensate. The only parameter, 'address', is referenced only as 'one Base address'. This adds the chain context (Base) but does not explain the required format beyond what the schema pattern shows, nor does it mention that the address is a string, checksummed, or that it must be a valid 0x-prefixed address. The description adds minimal semantic value over the parameter name itself.

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 uses a specific verb ('Read') and a specific resource ('native ETH balance for one Base address'), which immediately distinguishes it from siblings like base_erc20_balance (ERC-20 tokens) or base_wallet_snapshot (likely a broader overview). The phrase 'native ETH' makes the tool's scope unambiguous, and 'for one Base address' signals the singular input.

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 intended use case is clear and implied by the purpose: if you need the native ETH balance of a Base address, this is the tool. However, the description does not explicitly state when to prefer this over alternatives (e.g., base_erc20_balance for tokens, base_wallet_snapshot for a full wallet view), nor does it mention any exclusions or prerequisites. The cost note hints at usage considerations but does not provide comparative guidance.

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