get_roll_yield

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

Annotations already declare readOnly/idempotent/openWorld, so the safety profile is covered. The description adds real behavioral context beyond them: the df parameter is optional, data is fetched from dailyBar internally when df is null, and pre-feeding data speeds up computation. Return format and rate limits are still unstated, keeping it short of a 5.

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?

Front-loaded purpose sentence followed by a clean parameter list; there is little waste. Slightly awkward that the parameters block is embedded in the description rather than the schema, but the structure itself is efficient and readable.

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 5-param tool with no output schema, the description covers purpose and each parameter, which is reasonable. It is incomplete on the return value and, more importantly, on how it differs from the sibling get_roll_yield_bar, which an agent needs to select correctly.

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 carries the burden and largely does so, documenting all five parameters with types, formats (date as YYYYMMDD), and examples (variety RB/AL, contracts rb1810/rb1812). Minor gaps remain: it doesn't reconcile the schema default var='BB' with its own RB/AL examples, and symbol1/symbol2 vs. variety-selection interplay is only loosely defined.

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 gives a specific verb+resource: computing the 展期收益率 (roll yield) for a specified trading date and variety (main + secondary main) or for any two contracts. It is clear what the tool returns, but it never differentiates itself from the near-identical sibling get_roll_yield_bar, so an agent cannot route between them from the text alone.

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 implies the two invocation modes (by variety with 主力和次主力, or by an explicit pair symbol1/symbol2), which is useful usage context. However it names no alternative tool and gives no when-not-to-use guidance, leaving the choice against get_roll_yield_bar to inference.

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