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

No annotations are provided, so the description carries the full burden. It discloses the append action and the parameter modes, but it does not mention return values, error behavior, or permission requirements. The term 'append' implies non-destructive modification, but this remains implicit.

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, focused sentence with a short clarifying clause. It front-loads the primary purpose and gives just enough detail about parameter usage without unnecessary elaboration.

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 append tool, the description covers the essential context: what it does, the target resource, and the key parameter selection guidance. It lacks details about return values or error handling, but the absence of an output schema and the tool's straightforward nature make this acceptable.

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 input schema already describes all four parameters with 100% coverage, earning a baseline of 3. The description adds value by explicitly distinguishing the purposes of 'rows' (multiple rows) and 'values' (single row), which is not immediately clear from the schema alone.

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 action ('Append') and the target resource ('spreadsheet tab'), which distinguishes it from sibling tools like append_slides and append_to_document. It also further clarifies by describing the two modes of operation (multiple rows vs. single value).

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 explicit context: the tool is for appending data to a spreadsheet tab, and it gives a clear decision rule for when to use 'rows' versus 'values'. However, it does not explicitly name alternative tools or state when not to use this tool, so it stops short of a full 5.

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