is_contract

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

With no annotations, the description carries the full burden of behavioral disclosure. It implies a read-only check by using 'Check', but does not explicitly state whether it mutates state, how it handles invalid addresses, or what network behavior to expect. For a simple check tool this is adequate, but it lacks details such as error handling or response format.

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 is a single, focused sentence that immediately conveys the core purpose. It contains no redundant information or filler, and the key terms (smart contract, EOA, address) are front-loaded. Every word 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?

The tool is simple with two well-documented parameters, so the description's brevity is partially justified. However, there is no mention of the return value (e.g., boolean or classification), and no coverage of edge cases like network selection defaults. Given the absence of an output schema and the existence of overlapping siblings, the description feels minimally viable but not fully 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?

The input schema already provides descriptions for both 'address' and 'network' (100% coverage), so the description need not repeat them. The schema itself clearly explains each parameter (address to check, network name/chain ID with default). Therefore the description adds no extra parameter semantics, placing it at the baseline of 3.

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's function: checking if an address is a smart contract or an EOA. It specifies the verb 'Check' and the resource 'address', making the purpose unambiguous. However, it does not distinguish this from the similar sibling tool 'check_address_type', so it misses the differentiator needed for a 5.

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 provides no guidance on when to use this tool versus alternatives like 'check_address_type' or 'validate_address'. It only states what it does without any context on use cases, prerequisites, or exclusions. This leaves the agent without criteria for selecting this tool over similar checks.

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