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

With no annotations, the description carries the full burden. It discloses that values are read at the latest block (reorg risk) and states the cost ($0.008 USDC per call via x402 on Base). It also implies a read-only operation by listing balance/nonce/code, and the optional token param adds behavioral context. Missing are error handling, rate limits, or idempotency, but the disclosed caveats exceed the typical baseline.

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 three sentences with zero filler. It front-loads the core purpose, then the optional parameter, then caveats and cost. Every sentence serves a distinct purpose, and the structure is logical for an agent to scan quickly.

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?

Given no output schema, the description adequately conveys the return values (balance, nonce, contract status, optional token balance) and the operational context (chain default, cost, reorg risk). It doesn't mention response format or error behavior, but for a simple read-only call, the provided information is sufficient 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 coverage is 100%, so the schema already documents each parameter. The description adds context for 'token' (reads ERC-20 balance in same call) and frames 'address' as a prerequisite for sending, which slightly enriches semantics. However, it doesn't add syntax, formats, or interaction details beyond the schema, so the value-add is marginal.

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 returns native balance, next nonce, and contract-code status, with an optional ERC-20 balance via 'token'. It uses specific resource nouns and implies a read operation, distinguishing it from token_info by focusing on address state rather than token metadata. However, it doesn't explicitly name sibling tools or contrast itself with them, so it's clear but not maximally differentiated.

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 a clear use case ('the three things needed before sending from or to an address') and explains when to pass 'token'. It does not explicitly state when to use alternatives like token_info or gas_now, nor does it mention any exclusions. The guidance is implied rather than explicit, so it's adequate but not prescriptive.

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