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

With no annotations, the description carries the behavioral burden. It discloses the return value (id and link), the default location behavior, and the conditional requirement for parentFolderId. It does not address permissions or conflict behavior, but those are minor for a simple creation tool.

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 with no wasted words. The core action comes first, followed by return value and then the placement caveat. The structure is easy to parse and intentionally ordered.

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 creation tool with three parameters and no output schema, the description provides enough to invoke it correctly: required fields are implied by the schema, the optional parameter is explained, and the return value is stated. Minor gaps like overwrite behavior and permission requirements do not block correct use.

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 schema already documents mailbox and parentFolderId, and the description adds useful location semantics for parentFolderId. However, the required 'name' parameter has no schema description and the description does not clarify what the name refers to. With 67% schema coverage, the description only partially compensates for that 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?

The description clearly states the action ('Create'), the resource ('a new empty .xlsx workbook'), and the location ('in the user's OneDrive'). It also mentions the returned id and link, and the 'new empty' qualifier distinguishes it from tools like create_google_spreadsheet or add_excel_sheet.

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 gives practical placement guidance: the workbook lands in the top level of the drive unless parentFolderId is provided, and parentFolderId becomes required when mailbox access is folder-limited. It does not explicitly name sibling alternatives, but the context is clear enough for an agent to decide when to use this tool.

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