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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds substantial extra context: the exact slots read, that an upgradeable proxy's implementation can change after the read, that malformed/inconsistent node answers return 5xx uncharged, latency of 1-4s, pricing, and the shared free-tier rate limit. This is far beyond what the annotations provide.

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?

Front-loaded with the core action and inputs before the return field list, then caveats, latency, and pricing. It is a dense single-paragraph block, but nearly every clause carries operational value for a tool with this many return fields; minor density cost only.

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 full burden and does so thoroughly: it enumerates is_contract, is_proxy, kind (with all enum values), implementation and whether it has code, admin, beacon, and raw slots, plus the transient nature of the implementation for upgradeable proxies. Nothing an agent needs to interpret results is missing.

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 description coverage is 100% with an enum on `chain` and a regex pattern on `address`, so the schema already documents both parameters fully. The description restates the same input contract (ethereum|base, 0x+40 hex) without adding new syntax or semantic detail, so the baseline of 3 applies.

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 precise verb+resource: detecting whether a contract is a proxy and which kind, across two named chains. The enumerated `kind` values (eip1967_transparent, eip1822_uups, eip1167_minimal, etc.) make the scope unambiguous and clearly separate it from siblings like scan_contract_source or check_contract_before_interaction.

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?

The description makes the usage context inferable (you call it to classify a deployed contract), but it never explicitly says when to prefer this over siblings such as scan_contract_address, scan_contract_source, or check_contract_before_interaction. No when-not guidance or alternative routing is offered.

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