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

With no annotations, the description carries the full burden and does well for a simple read: it pins the network (Base mainnet), names the RPC call, and discloses the return semantics (bytecode size, zero for an externally-owned account). It omits whether any auth/rate limits apply, but the safety profile is unambiguous.

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?

A single, front-loaded sentence with no filler: purpose first, then the mechanism, then the return contract. Every clause earns its place.

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 one-parameter read tool with no output schema, the description covers the essentials: network scope, method, and what the returned number means. The remaining gap is the undocumented nested payload/address structure.

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 0% and there is one nested parameter object, so the schema documents nothing. The description implies the address input ('a Base mainnet address') but does not explain the required 'payload' wrapper object or the address format, leaving the nesting entirely to the schema.

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 (check) and resource (whether a Base mainnet address is a contract), and names the underlying RPC method eth_getCode. It is clearly separable from siblings like base_nonce, base_block, or base_tx, though it never explicitly routes the agent away from any alternative.

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?

Usage is only implied: an agent infers it should call this when it needs to know if an address is a contract vs an EOA. There is no explicit when-to-use statement, no prerequisites, and no mention of when another base_* tool would be the better choice.

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