Create a virtual sub-account under a Binance master account by supplying the sub-account email and master API key, enabling separate account management.
Create a virtual sub-account under the master account. Requires master account API key.
| Name | Required | Description | Default |
|---|---|---|---|
| recvWindow | No | The value cannot be greater than 60000 | |
| subAccountString | Yes | The email address for the virtual sub-account |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the full burden. It does disclose the authentication requirement (master account API key), which is real behavioral context. But it omits the fact that this is an irreversible mutation, any quota/limit on virtual sub-accounts, and what the callback returns (e.g., the new sub-account identifier).
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, zero filler, and the mutation intent is front-loaded ahead of the auth prerequisite. 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?
The tool is simple (2 params, flat schema), so the description is nearly sufficient. But for a create/mutation operation with no annotations and no output schema, one would expect a note about irreversibility and the shape of the response (e.g., the created sub-account identifier).
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 100%, with both subAccountString ('The email address for the virtual sub-account') and recvWindow ('cannot be greater than 60000') fully documented. The description adds nothing beyond the schema about parameter format or constraints, so the baseline 3 applies.
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 and resource: 'Create a virtual sub-account under the master account'. It is clearly distinguishable from read-oriented siblings such as BinanceSubAccountGetList and BinanceSubAccountGetAssets. It stops short of naming a sibling outright, so a 4 rather than 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 states a prerequisite ('Requires master account API key'), which is genuinely useful context. However, it gives no guidance on when to use this versus alternatives like BinanceSubAccountCreateApiKey or BinanceSubAccountEnableFutures, and no exclusions or preconditions such as account limits.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.