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

With no annotations, the description must carry the behavioral burden. It signals a read-only operation and mentions output units, but it does not disclose the response shape, behavior for invalid addresses, or any RPC/network caveats. There is no contradiction with annotations because annotations are empty.

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 a single front-loaded sentence with no filler. It packs the resource, network, and output units into minimal text, every word earning 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 simple one-parameter read operation, the description is largely complete: it states the resource, network, and units. It lacks an explicit response format and alternative-tool guidance, but the low complexity and lack of output schema make those gaps relatively minor.

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 0%, but the only parameter is 'address' and its regex fully constrains the format. The description's phrase 'an address native ETH balance' clarifies that the address is the account being queried, which meaningfully supplements the schema despite the low coverage.

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 states a specific verb ('Read'), a clear resource ('address native ETH balance'), a network ('Base mainnet'), and output units ('wei and ETH'). It also differentiates from sibling tools like base_erc20_balance by specifying native ETH rather than a token balance.

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 about what this tool reads and on which network, so an agent can infer it is for native ETH rather than ERC-20 tokens. However, it does not explicitly name alternatives or state when not to use this tool, leaving some routing to inference.

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