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

Annotations already indicate read-only, open-world, and idempotent behavior, and the description adds substantial detail beyond that: zero balances are explicitly flagged, non-balanceOf contracts return found:false, symbol and decimals are resolved in the same call, and there is no API key requirement. No contradiction with annotations.

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 core purpose and then efficiently adds edge-case, failure-mode, and pricing information. Every sentence adds useful information without redundancy.

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 two-parameter read tool with an output schema, the description covers the essential edge cases (zero balance, unsupported contract), the resolved return data, and operational requirements like cost and authentication. Nothing critical is missing for an agent to invoke it 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 description coverage is 100%, so the parameters are already documented. The description confirms that token and wallet are required inputs and adds that token is an ERC-20 contract on Base, but it does not provide additional format or validation semantics beyond the schema.

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 and resource: 'One wallet's balance of one token — An ERC-20 balance on Base'. It also clarifies scope and return content, distinguishing it from broader wallet or token-level tools like wallet_tokens or token_supply.

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 prerequisites ('Required inputs: token, wallet') and useful context about pricing and authentication requirements. However, it does not explicitly state when to prefer this tool over sibling alternatives or when not to use it, leaving usage selection mostly implied.

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