evm_balanceNative coin balance (ETH, MATIC...) for any address, on Base, Ethereum, Polygon, Arbitrum or Optimism. Flat price, no rate limits, no API key. Flat $0.001 per call, paid over x402 (USDC).
| Name | Required | Description | Default |
|---|---|---|---|
| chain | No | base | ethereum | polygon | arbitrum | optimism. Defaults to base. | |
| address | Yes | 0x-prefixed address to look up. |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral transparency burden. It explicitly discloses pricing ($0.001 per call), payment method (x402/USDC), and states 'no rate limits, no API key'. It does not explicitly state the call is read-only, but that is inherently obvious from a balance lookup; the disclosed information is sufficient.
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 concise, front-loaded with the main purpose, and includes essential extra information (pricing, payment) in a second sentence. No redundant or filler content.
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 description covers functionality, supported chains, default behavior, pricing, and payment method. It does not describe the output or return format, but since no output schema is provided and the result is a simple balance, this omission is not a major gap. Overall, the context 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?
Both parameters (address and chain) are clearly described in the schema. The chain parameter enumerates valid values and states the default ('base'), while address specifies the expected 0x-prefixed format. The schema covers 100% of parameters, and descriptions add necessary clarity.
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 purpose: retrieving the native coin balance (ETH, MATIC) for any address on five named chains. It distinguishes from sibling tools like evm_erc20_balance by specifying 'native coin balance' and lists supported networks, so an agent can immediately understand what the tool does.
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 practical usage context by listing supported chains, the default chain, and pricing/payment details. It does not explicitly mention when to use this tool versus an alternative (e.g., 'use evm_erc20_balance for token balances'), but the scope is clear enough to guide selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.