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

Annotations already establish read-only, non-destructive, idempotent behavior. The description adds valuable behavioral context by emphasizing 'point-in-time' and 'one resolved Base mainnet block,' indicating all reads are consistent at the same block. It also clarifies that native USDC and ETH are always included while other tokens are optional, which the annotations do not convey.

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?

A single, concise sentence that front-loads the action ('Read') and packs in all essential details without redundancy. No filler words, and the structure is easy to parse.

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?

The tool has a rich output schema, so return values need no explanation. The description covers the key behavioral aspects: what data is read (ETH, USDC, ERC-20s, nonce, code status), the block resolution semantics, and the optional token selection. It is complete for an agent to understand when and how to invoke the tool.

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 baseline is 3. The description adds meaning by clarifying that ETH and native USDC are always included in the snapshot, while token_contracts is optional and limited to four ERC-20s. It also explains the significance of the block_tag as the resolved point-of-consistency, going beyond the schema field descriptions.

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 identifies the exact resource: point-in-time ETH, native USDC, up to four caller-selected ERC-20 balances, account nonce, and contract-code status at one resolved Base mainnet block. This clearly distinguishes it from sibling tools like crypto.base-account-status, which likely provides a simpler current-state view.

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 conveys clear context: it is for reading a consistent snapshot at a chosen block, including token balances beyond the native asset. However, it does not explicitly name alternative tools or state when not to use it, so it stops short of full explicit exclusion guidance.

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