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

Annotations declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false. The description adds the nuance that this also tells you whether the address is a contract by checking code presence, and implies this is a lightweight read. It doesn't mention gas costs or that contract account code may change, but it's adequate given the annotations already communicate safety.

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 description consists of only two sentences that pack significant meaning: the first lists the returned fields, the second explains the EOA/contract distinction. No wasted words.

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?

Given the low complexity (3 flat params, no output schema needed for a simple read), the description adequately covers the tool's purpose. It could benefit from a brief note on the output shape, but since no output schema is required and params are well-documented, this is nearly complete.

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 the schema describes each parameter (block, address, network) with defaults. The description doesn't need to add param semantics since the schema is complete and precise. Baseline 3 is appropriate.

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?

The description clearly states the tool returns balance, nonce, and code presence for an address, and explains how to distinguish EOA from contracts. It uses specific nouns (balance, nonce, code) beyond the tool name. It doesn't explicitly distinguish from siblings like read_transaction or call_contract, but the resource and outputs are specific enough to guess.

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 implies usage for account-level queries and provides a decision rule for EOA vs contract. However, it doesn't explicitly state when NOT to use it or name alternative tools, though the 'code presence' explanation hints at contract inspection. Sibling names like chain_info and read_contract are present, so some cross-referencing guidance would improve it.

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