Binance.US MCP Server

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

No annotations are provided, so the description carries the full burden. It discloses key behavioral traits: the requirement for a custodial API key (auth needs) and that it returns balance for placing new orders (read-only, non-destructive operation). It doesn't mention rate limits, error conditions, or response format details, but given the lack of annotations, it provides sufficient basic context for a read operation without contradictions.

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 appropriately sized and front-loaded: it starts with the core purpose, includes a critical warning, and ends with the return value clarification. Every sentence earns its place, with no wasted words, making it efficient and easy to parse.

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 the tool's complexity (a read operation with specific auth requirements), the description is complete enough: it covers purpose, prerequisites, and return value intent. No output schema is provided, but the description clarifies what the return represents. It lacks details on response format or error handling, but for a balance query tool, this is adequate, though not exhaustive.

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 has 100% description coverage, with clear documentation for both parameters ('rail' and 'asset'). The description doesn't add any parameter-specific information beyond what the schema provides (e.g., no examples or usage tips for parameters). Since schema coverage is high, the baseline is 3, as the description doesn't compensate with extra semantic details.

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: 'Get available balance in the custodial sub-account for trading.' It specifies the verb ('Get'), resource ('available balance'), and scope ('custodial sub-account for trading'), which distinguishes it from general balance tools. However, it doesn't explicitly differentiate from sibling tools like 'binance_us_cust_balance' or 'binance_us_custodial_balance', which appear similar, so it misses full sibling differentiation.

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 clear context for usage: it specifies that this is for 'trading' and includes a warning '⚠️ REQUIRES CUSTODIAL SOLUTION API KEY,' indicating prerequisites. It also clarifies the return value's purpose: 'Returns the balance available for placing new orders.' However, it doesn't explicitly state when to use this tool versus alternatives like 'binance_us_cust_balance' or other balance-related siblings, so it lacks explicit alternatives guidance.

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