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

Beyond the annotations, the description discloses the return shape (32-byte word as a number and conditionally as an address), malformed-input behavior (400, uncharged), failure charging, and pricing. These details materially help an agent understand cost and error semantics for this read-only call.

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 description is front-loaded with the core purpose and slot semantics before moving to usage, error behavior, and pricing. It is dense but mostly earns its space; the pricing sentence is relevant but makes the description longer than strictly necessary.

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 two-parameter read-only tool with no output schema, the description covers purpose, slot format, return shape, alternative tooling, error behavior, and charging. An agent has 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 coverage is 100%, so the schema already defines both parameters. The description adds useful context by explaining that slot values may be mapping or proxy slots and by giving an example address format, going slightly beyond the schema text.

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 verb and resource — reading one raw storage slot of a contract on zkSync Era — and explicitly maps it to eth_getStorageAt. It also distinguishes the tool from zksync_proxy, so an agent can choose correctly without opening either 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?

It gives an explicit usage condition: inspect contract state that has no getter, owners, or implementation pointers. It also names the alternative zksync_proxy for proxy-related work, which is exactly the sibling-routing guidance needed.

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