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

Annotations already mark readOnlyHint and destructiveHint false, but the description adds useful behavioral context: it reads three data points (ETH, USDC, and block height, indicating it fetches a snapshot of current on-chain state). This enriches the definition without contradicting the annotations.

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?

A single sentence with zero fluff. It front-loads the core verb (Read) and lists resources directly. Every word contributes to clarifying what part and what data is involved.

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 that the tool presumably has an output schema (present) and safety-related annotations, the description sufficiently covers selection and invocation context. It does not mention a possible usage fee hinted by the title, but it is not a functional block for a light read filter. The coverage of block height indicates awareness of the important state context.

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 only parameter, address, has 100% schema coverage including pattern and description, so the tool description adds no new semantics beyond what is already in the schema. Baseline 3 applies because the schema already fully documents the input.

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?

Clearly identifies the operation with specific verb 'Read' and states exact resources: native ETH, Circle USDC balances, and current block height for a Base wallet. This is unambiguously distinct from its siblings, which all stay in URL/merchant/payment domains.

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 implies use when you need Base wallet balances, but it does not explicitly say when-to-use or provide when-not-to-use guidance. There are no obvious alternatives among siblings, so the absence of exclusions is acceptable, but the lack of explicit guidance leaves it at baseline.

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