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 this with 'Reads or computes only and changes nothing', plus the important caveat that each call is charged so repeats are not free (consistent with idempotentHint=false). It adds pricing, free-tier, and failed-call-cost context that annotations cannot express, but it does not describe the concrete response shape (e.g., boolean field names, proxy implementation field), so the disclosure is strong on cost and safety but incomplete on output behavior.

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 is front-loaded in the first sentence, then usage, then error behavior, then a concrete example, then pricing. Despite covering many topics it stays to a handful of sentences with no filler; the pricing clause is the only part that could be trimmed slightly.

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 single-parameter read-only chain lookup with no output schema, the description covers purpose, alternatives, error handling, example input, cost, and non-mutation guarantees — everything an agent needs to select and call 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% and there is only one parameter, so the baseline is 3. The description goes slightly beyond the schema by supplying a concrete example address and by specifying the rejection behavior when the address is malformed, which helps the agent format the argument correctly.

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 ('Check whether a 0x address on Scroll is a smart contract or a plain wallet') and enumerates what is returned: bytecode size, EIP-1167 minimal proxy status, and the implementation it points to. This distinguishes it from nearby siblings like scroll_proxy and scroll_call, which an agent could otherwise confuse it with.

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 when-to-use ('before sending funds or approving a spender') and names the alternative for a different job ('for a fuller risk verdict use check_counterparty'). It also tells the agent what happens on bad input (malformed address rejected with 400, uncharged), so preconditions are covered.

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