vtable_get_cell_center

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

With no annotations, the description carries the full burden. It discloses the coordinate space (top-level viewport), the computation method (scene graph globalAABBBounds), and that iframe/container offsets are included. This is rich behavioral context beyond the schema. It doesn't explicitly state read-only, but '读取' (read) implies it, and the description adds valuable details about the calculation and use case.

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 two concise sentences, front-loading the core outcome (viewport coordinates) and the intended use (click_interact). The second sentence efficiently clarifies parameter semantics. Every word earns its place, with no redundancy or fluff.

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?

The tool is moderately complex (computes coordinates with iframe/container offsets) but the description covers the essential aspects: purpose, parameter semantics, coordinate space, and how to use the output. Since an output schema exists, return-value details aren't needed. It doesn't discuss edge cases or errors, but for a read-only getter with these annotations, it's adequately complete.

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 must compensate. It explains col_field (supports column index, field name, or column title) and row_index (pure data row number, 0-based). This adds meaning beyond the raw schema. However, the optional iframe_selector parameter is not mentioned, leaving a small gap in an otherwise well-documented set.

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: reading cell center top-level viewport coordinates. It uses a specific verb ('read') and resource ('cell center coordinates'), and differentiates from sibling tools like vtable_get_cell_text by explicitly focusing on coordinates for clicking. The direct reference to click_interact further clarifies its unique role.

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 when to use the tool: when you need clickable coordinates for a cell, specifically as input to click_interact. It implicitly distinguishes from text/render-info getters, though it doesn't explicitly name alternatives or state when not to use. The instruction that coordinates can be directly used for click_interact is a strong usage guideline.

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