get_balance

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. It does disclose the authentication requirement, which is key behavioral context. However, it does not state that the operation is read-only, whether there are any rate limits or side effects, or what the response format will be. Since the output schema exists, return format is covered there, but the description offers minimal behavioral transparency beyond the prerequisite. This is adequate but not rich, warranting a 3.

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 one short sentence that front-loads the core purpose and then adds the key prerequisite. Every word earns its place; there is no redundancy or fluff. This is a model of conciseness.

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 has no parameters and an output schema exists, the description is largely complete. It covers the essential purpose and the auth prerequisite, which are the main contextual gaps an agent might need. It could potentially mention that it fetches the balance for the current tenant context, but that is already implied by '当前租户'. A 4 reflects that it is sufficient but not exhaustive – for instance, it doesn't clarify whether the balance is for tokens specifically used in this MCP server, though that is likely unambiguous. Minor gaps exist but none are critical.

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 there is nothing for the description to add beyond the schema. The baseline of 4 is appropriate because there is no semantic gap to fill. The description correctly omits parameter 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 states a specific action ('查询' – query) and a clear resource ('当前租户的 Token 余额' – current tenant's token balance). It naturally distinguishes itself from sibling tools chat_completion and list_models, as balance checking is an unrelated operation. The purpose is unambiguous and complete.

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 explicitly mentions a prerequisite: '需配置 MCP_API_KEY 识别租户' (requires configuring MCP_API_KEY to identify the tenant). This tells the agent when the tool is usable. It does not explicitly state when not to use it versus alternatives, but the tool's function is so distinct from its siblings (chat and model listing) that no further routing guidance is needed. A 4 is appropriate for clear context without explicit exclusions.

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