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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=true, so safety framing is partially redundant rather than additive. What the description genuinely adds is cost behavior (per-call charge, repeats not free, failures uncharged) and the failure taxonomy (400 malformed vs 404 no code) — useful, but the pricing paragraphs are commercial boilerplate that wouldn't change a tool-selection decision. It stops short of saying what the response contains beyond 'names the kind found'.

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 capability and the alternative routing are front-loaded in the first two sentences, which is the right ordering. Efficiency is slightly hurt by three clauses of payment/credits detail at the end that most callers won't act on, but nothing is genuinely redundant.

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, the description still indicates the return content ('names the kind found') and lists the proxy standards checked, which is enough to set expectations. Failure modes and cost are covered; only the exact shape of the response is left to discovery, a minor gap for a single-parameter read tool.

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?

Only one parameter and schema description coverage is 100%, so the schema already carries the meaning and the baseline is 3. The description does add a concrete address example and implicitly ties the parameter to the Arbitrum chain, which is modest added value, but no format constraints beyond the schema's '0x contract address'.

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 ('Find the implementation behind a proxy contract on Arbitrum One') and enumerates exactly which storage slots / bytecode patterns it inspects, so an agent knows the precise capability. The chain is named, which separates it from the eth_proxy/base_proxy/op_proxy/polygon_proxy siblings despite the parallel naming scheme.

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 condition ('before trusting or decoding a contract whose code can be swapped by its admin') and an explicit alternative with a selection rule ('for a fuller risk verdict use contract_risk'). The 400/404 semantics also tell the agent what failure looks like without trial and error.

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