vtable_get_row_count

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

With no annotations provided, the description carries the full burden. It discloses important behavioral traits: it reads internal record collection length and is not affected by screen scroll truncation, which tells the agent this is a non-destructive, direct read. It also scopes to '纯数据' (pure data), clarifying it excludes headers/UI chrome. This goes beyond the simple function name, though it doesn't mention side effects or permissions (which are likely minimal for a getter).

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 a single sentence that front-loads the main purpose and then adds two key behavioral details ('directly reads internal record collection length', 'unaffected by scroll truncation') with no wasted words. It sets a good balance of brevity and substance.

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 simple getter tool with an output schema present, the description adequately covers the core function and the unique aspect of scroll-independent counting. The main gap is the unexplained `iframe_selector` parameter, which is optional and defaults to a reasonable selector, so it does not severely impair completeness. The presence of an output schema covers return-value expectations.

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 single parameter `iframe_selector` has zero schema description coverage (no description in the schema), and the tool description does not mention it at all. The parameter's purpose is left entirely to inference from its default value, which is insufficient compared to the baseline of 3 for covered schemas.

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: '读取当前 VTable 表格有多少行纯数据' (read how many rows of pure data the current VTable table has). It uses a specific verb ('读取') and resource ('当前 VTable 表格'), and the additional detail '不受屏幕滚动截断影响' distinguishes it from visible-row count methods, setting it apart from sibling vtable tools.

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 that it reads the internal record collection length and is unaffected by scroll truncation, implying it is the tool to use when a true data row count is needed regardless of scroll position. However, it does not explicitly name alternatives or state when not to use it, so it falls short of a 5.

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