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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces the read-only, non-transactional nature. It adds valuable behavioral context beyond the annotations by disclosing the exact cost ('$0.005 USDC via x402'), which is important for an agent deciding whether to invoke it.

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?

Two sentences, no filler. The first sentence defines the core behavior and scope, and the second adds the cost. Every word earns its place.

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 three-parameter read-only tool with rich schema descriptions and safety annotations, this description is complete. It states the network, the method, the non-transactional nature, and the cost, giving an agent everything needed 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 description coverage is 100%, so each parameter (to, data, block) is already well-documented in the schema. The description adds no additional parameter-level meaning, which matches the baseline of 3 since the schema carries the documentation burden.

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 names a specific operation ('read-only smart-contract call'), the exact RPC method ('eth_call'), the network ('Base'), and explicitly states it does not send a transaction. This clearly separates it from the transaction-oriented sibling tools like base_receipt and base_transaction.

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 read-only characterization and 'without sending a transaction' provide clear context for when this tool is appropriate: any contract state read on Base. It does not explicitly name alternative sibling tools or exclusions, but the usage context is strong enough for an agent to distinguish it from write or transaction-related tools.

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