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

Beyond the annotations, it discloses that the tool does not return data directly but returns an exact paid x402 request (GET /evm/nonce) that must be called with an x402 or MPP client, adds pricing ($0.001 per call), and notes that bad input is refused before any charge. This is meaningful behavioral context about cost, indirection, and error handling that annotations do not cover.

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 trigger is front-loaded and the content is dense but purposeful, with each clause carrying distinct information (scope, outputs, price, indirection, error handling). It is slightly lengthy in the second sentence but not wasteful.

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?

With no output schema, the description compensates by explaining exactly what is returned (the paid request plus response schema and example) and how to obtain the data. An agent has everything needed to invoke it correctly despite the two-step x402 pattern.

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%, with the address pattern and chain enum already documented in the schema. The description restates the chain names and the account concept but adds no format or syntax detail beyond the schema, so the baseline of 3 applies.

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 resource (an account's nonce / transaction count) and two distinct outputs (nonce at latest block and pending nonce from the pool), and it enumerates the supported chains. This clearly distinguishes it from siblings like evm_transaction, evm_block, and wallet_balance.

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 opens with an explicit trigger ('Use when you need an account's transaction count'), giving a clear condition for selection. It stops short of naming an alternative or stating when NOT to use it, so it does not reach the 5 level.

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