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

Annotations declare non-read-only, non-destructive, but say nothing about type coercion. The description discloses a genuinely useful behavior: values parse as if typed, a leading "=" becomes a live formula, and there is no raw-text escape hatch. That is real context beyond the annotations, though it omits error/permission behavior.

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 sentences, front-loaded with the core append behavior and no wasted preamble. Slight redundancy: the first and third sentences both restate that values are interpreted as typed.

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 mutation tool with no output schema and two undocumented parameters, the description covers value interpretation well but is silent on what happens on failure, whether the target sheet must exist, and what the call returns. Adequate but with clear gaps.

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 50% (workbookId and sheet are undocumented), and the description adds meaning only about how values are interpreted rather than clarifying the undocumented parameters. The value-interpretation detail is helpful but does not compensate for the coverage gap.

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?

"Add rows after the last row holding data" states a specific verb (add/append), resource (worksheet rows), and a precise insertion point, which implicitly separates it from overwrite-style siblings like update_excel_range. It stops short of naming an alternative sibling explicitly, so an agent must still infer the contrast.

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 usual way to add records to a tracker" gives implied usage context for appending records. There are no explicit when-not conditions or named alternatives (e.g. use update_excel_range when you want to overwrite an existing range), leaving routing to inference.

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