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

Adds a lot beyond the annotations: malformed address or slot returns 400 uncharged, pricing ($0.01/call via x402 USDC or card key, first 25 free), failed calls free, and the explicit note that repeats are charged. That last point explains why idempotentHint is false for what is otherwise a pure read, heading off a likely agent assumption. It stops short of full marks only because pagination/response envelope details are absent, though there is little to say for a single-slot 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?

Purpose and the eth_getStorageAt mapping are front-loaded, and the alternative routing follows immediately. The tail is dense with pricing clauses, and 'each call is charged, so repeats are not free' partially restates the price sentence, costing a little efficiency without obscuring the message.

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 with no output schema, the description covers return format, error behavior, cost, and sibling routing. An agent has everything needed to call it correctly and to anticipate the charge.

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 and the baseline would be 3. The description adds real meaning on top: it clarifies the two slot encodings are for distinct cases ('mapping and proxy slots'), which the schema does not say, and supplies a concrete address example. The required-vs-optional distinction is left to the schema.

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 and resource ('Read one raw storage slot of a contract on Gnosis'), names the underlying RPC method (eth_getStorageAt), and describes the return shape (32-byte word as number, and as address when applicable). It is clearly distinguishable from the sibling family, which has no other storage-read naming besides per-chain *_storage variants.

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?

Gives an explicit usage condition ('inspect contract state that has no getter, owners or implementation pointers') and routes the agent to the alternative when that condition fails ('for proxies use gnosis_proxy'). Nothing is left to inference.

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