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

With no annotations, the description carries the full behavioral burden and does disclose key facts: no API key, no account, and a $0.005 per-call x402 USDC payment requirement. It also explains what the pending nonce is for. It could be stronger by explicitly stating the operation is read-only and describing any rate-limit or error behavior.

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 primary usage condition and packs output semantics, exclusions, auth, and pricing into a small number of useful sentences. Every sentence earns its place, with no redundant or vague filler.

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?

Because there is no output schema, the description usefully explains the return values: confirmed nonce, pending nonce, and whether the address is a contract. It also covers payment and auth. A small gap remains around what happens when the optional chain parameter is omitted, such as a default chain.

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 schema already documents both address and chain, including the supported chain values. The description adds no parameter-level detail beyond the schema; it only explains the semantic meaning of the pending nonce in the output, so the baseline of 3 is appropriate.

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 resource and purpose: fetching the confirmed nonce, pending nonce, and contract status for an EVM address. It distinguishes itself from evm_balance and evm_estimate_gas, though it does not explicitly address overlap with the sibling evm_is_contract even though contract status is one of the returned values.

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?

It gives an explicit use case ('when an agent signs transactions one after another and must not collide with one already in flight') and explicit exclusions with alternatives for affordability checks (/v1/evm/balance and /v1/evm/estimate-gas). This is exactly the kind of routing guidance an agent needs.

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