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

Beyond the readOnlyHint and idempotentHint annotations, the description discloses a key edge-case behavior: when the chain cannot be reached, the tool will explicitly say so rather than returning a zero balance, which is semantically different. This is valuable behavioral context that the annotations do not provide.

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 and reasonably concise. The first sentence front-loads the main purpose, while the second adds important behavioral nuance. It is slightly wordy ('Says so plainly...') but every phrase serves a purpose, so it earns a solid 4.

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 parameterless read-only tool, the description is largely complete. It states what is checked and how an edge case (chain unreachable) is handled. It does not describe the exact return format, but with no output schema, a simple balance tool likely needs no further detail. The annotations cover safety, making this adequate.

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?

The tool has zero parameters, and the schema already reflects that (100% coverage). The description adds no parameter details because there are none to add. Baseline for 0 params is 4, and the description does not need to compensate for anything.

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 clearly states the tool's function: checking what a wallet holds in USDC on Base. The resource and specific scope (USDC on Base) are precise, and the phrasing distinguishes it from sibling tools like wallet_pay (which sends) and wallet_list (which likely lists wallet accounts or transactions). The verb is implicit but clear.

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 no explicit guidance on when to use this tool versus alternatives. It does not mention wallet_pay or wallet_address or provide any exclusion criteria. The intended use case is implied by the purpose, but there is no direct comparison or contextual advice.

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