Balance of an address on Base or Ethereum, in ETH or USDC.
Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {
"address": "<address>",
"chain": "<chain>"
},
"name": "get_balance"
}
}| Name | Required | Description | Default |
|---|---|---|---|
| unit | No | ||
| chain | Yes | ||
| address | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure, and it discloses almost nothing beyond the resource itself. It omits whether the call requires auth/API key, whether there are rate limits, what happens for an address with no funds or a malformed address, and what form the returned balance takes (raw wei vs decimal, string vs number).
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; the scope and denomination are stated up front. It is efficient, though it is arguably too terse given the gaps it leaves on a 3-parameter tool.
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?
With no annotations, no output schema, and 0% schema description coverage, the one-sentence description is not sufficient for an agent to call this confidently. It never specifies the return value semantics, the unit default, or the address format, all of which the agent must guess.
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 description coverage is 0%, so the description must compensate for three undocumented parameters. It only re-states the enum values for chain and unit as prose ('Base or Ethereum', 'ETH or USDC') without adding any new meaning, and it says nothing about the required address format or the default for the optional unit parameter.
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 resource (the balance of an address), the supported chains (Base, Ethereum), and the denomination (ETH, USDC), so an agent can tell it apart from coin_price, crypto_news, and get_block. It does not explicitly contrast itself with those siblings, but the noun phrase is unambiguous.
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?
No when-to-use guidance, no prerequisites, no alternatives named. The description never says which chain to prefer or when to pick ETH vs USDC, and it gives no hint about what happens if the optional unit parameter is omitted.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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