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

Annotations already declare readOnlyHint=true, so the safety profile is covered, but the description adds real behavioral context the annotations do not: every invocation is billed, billing flows through three account channels, and multi-symbol queries still count as one call. It does not cover failure modes or rate limits, but the cost/billing disclosure is substantial added value.

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?

Three tightly packed clauses: purpose with return fields, cost model, then batching rule. Information is front-loaded and nothing is filler, though the batching detail is duplicated verbatim from the schema.

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?

For a one-parameter read tool with no output schema, the description supplies both the shape of the returned quote fields and the billing consequence, which is the main risk an agent needs to weigh. Only error behavior and freshness/latency expectations are left unstated.

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 coverage is 100% and the single goldid parameter already documents comma-separation, the 50-item cap, example values, and the pointer to list_varieties. The description restates the same batching details rather than adding new semantics, 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 names a concrete resource and scope (实时贵金属行情) and enumerates what comes back (最新价、涨跌、买卖价、最高最低), so an agent knows exactly what this returns. The 'realtime' framing implicitly separates it from get_history and get_kline, but no sibling is named explicitly.

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?

It gives strong operational guidance in the form of a cost warning and batching advice (query up to 50 symbols in one call, still billed once), which shapes how an agent should invoke it. It does not state when to prefer get_history or get_kline instead, so tool-selection guidance is only implied.

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