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

With no annotations, the description carries the burden and adds useful behavior: return shape includes raw wei, formatted units, and the block number, and settlement only occurs on successful reads. It does not cover auth or rate-limit behavior, but the pricing and error-cancellation semantics are valuable disclosure.

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 purpose and supported chains are front-loaded, followed by return contents and payment terms in one dense but useful sentence. It is appropriately sized, though the pricing parenthesis is slightly separated from the core description.

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 read-only balance lookup with no output schema, the description explains what is returned (raw wei, formatted units, block) and the payment model. It is nearly complete, with only minor gaps around failure modes beyond settlement cancellation.

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 chain, address, and paymentSignature are already documented. The description reinforces chain coverage and address scope but adds little syntax or format detail beyond the schema, making the baseline 3 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?

States a specific verb-equivalent operation and resource: reads native coin balance for any address across named chains. The word 'native' distinguishes it from sibling chain_token_balance, so an agent can select correctly without inspecting the schema.

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?

Clear context is given: use for native coin balances on supported chains, and the accepted chains are listed. It does not explicitly name alternatives such as chain_token_balance or state when not to use this tool, so it stops short of full routing guidance.

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