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

Beyond the annotations (openWorld, idempotent, non-destructive) the description adds valuable behavioral context: a concrete cost of 0.005000 test USDC paid on a separate chain (eip155:84532) and a retry instruction. This cost disclosure also usefully explains why readOnlyHint is false despite the word 'Read'.

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?

Three short sentences, front-loaded with the purpose and no filler. Every sentence carries concrete information (chain, cost, retry key), making it tight and scannable.

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 and 50% parameter coverage, the description should explain return values (contract bytecode) and the params shape, but it does neither. For a 2-required-param tool it leaves key invocation and interpretation details unstated.

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 only 50%: idempotencyKey is documented in the schema, but the params array (address plus block tag/number/hash) is undocumented there. The description only echoes idempotencyKey retry advice and adds nothing about the actual eth_getCode parameters, so it fails to compensate for the coverage gap.

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 says 'Read eth_getCode from Ethereum (eip155:1)', giving a verb+resource and pinning the network, but 'eth_getCode' merely restates the tool name. It never explains what the method actually does (retrieve contract bytecode at an address), so it only helps agents already fluent in EVM RPC semantics.

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?

There is no when-to-use/when-not guidance and no routing advice. The description names the network and cost but never distinguishes this tool from the many sibling methods like eth_getBalance or eth_getStorageAt, leaving the agent to infer usage context entirely.

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