list_chainsList built-in EVM chains with chain IDs and explorers to select a network for contract analysis, or pass a custom rpc_url for any other chain.
List built-in EVM chains with their chain IDs and explorers. Any other network works by passing rpc_url.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint annotation already declares the tool as read-only, and the description adds behavioral context by stating it lists chain IDs and explorers, and that custom networks are handled elsewhere. This supplements the annotation without contradiction.
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?
Two sentences, both directly useful. The first states the core function, the second clarifies a related behavior (custom networks) without verbosity. 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 zero parameters, no output schema, and a readOnlyHint, the description fully covers what an agent needs: what the tool returns (chain IDs and explorers) and the important note that custom networks are handled via rpc_url elsewhere. Nothing essential is missing for a simple listing tool.
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 tool has zero parameters, so the baseline is 4. The description adds value by specifying what the output contains (chain IDs and explorers), which is the only semantic needed for a parameterless listing tool.
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 uses a specific verb (List) and resource (built-in EVM chains) and specifies the key output fields (chain IDs and explorers). It clearly distinguishes itself from the sibling tools, which are all about code analysis or execution, not chain enumeration.
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 when to use the tool: when you need to know which built-in chains are available. It also notes that custom networks don't require listing ('Any other network works by passing rpc_url'), which prevents misuse. However, it does not explicitly name an alternative or state when not to use it, but the purpose itself is self-explanatory.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.