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

Goes well beyond the annotations by disclosing error semantics (malformed address = 400, no code = 404, both uncharged), pricing ($0.01/call, first 25 free, failed calls free), and the fact that repeat calls cost money — which explains the otherwise puzzling idempotentHint=false. It restates 'reads or computes only and changes nothing', which the readOnlyHint already covers, and does not describe the shape of the returned record.

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 clause, followed by usage, then errors and pricing in a logical order. It is dense and slightly over-packed (standards list plus pricing plus error codes in one paragraph), but nearly every clause carries actionable information.

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 carries the burden of explaining returns; it says which slots are read and that the kind is named, plus error codes and cost, which is enough to call it correctly. It stops short of specifying the concrete response fields (implementation, beacon, admin, kind) for a non-proxy case.

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% for the single required 'address' parameter, so the baseline is 3. The description adds value with a concrete example address that demonstrates the expected 0x hex format, and by tying a malformed address to a 400 response.

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 Mantle' — and enumerates exactly which slot standards it resolves (EIP-1967 impl/beacon/admin, EIP-1822/UUPS, legacy OZ layout, EIP-1167 minimal proxy) plus that it names the kind detected. This clearly separates it from mantle_is_contract, mantle_storage and mantle_call without the agent needing to open any 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?

Gives an explicit trigger ('Use before trusting or decoding a contract whose code can be swapped by its admin') and names the alternative for a different need ('for a fuller risk verdict use contract_risk'). The when-to-use condition is tied to a concrete risk scenario rather than left implicit.

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