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

Annotations already declare readOnlyHint=false, openWorldHint=true, and idempotentHint=false. The description adds real behavioral context beyond that: when the plan's execution status is not executable, nothing is created and the access choices are returned instead — a non-obvious failure mode worth knowing. It stops short of describing permissions/auth needs or repeat-call behavior for the Google Sheets platform.

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?

Four sentences, front-loaded with purpose and output, then prerequisites, then the failure-mode caveat. The parenthetical about SheetsFinance functions coming from blocks and requirements is slightly nested but earns its place by preventing a common misuse.

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 single-parameter mutation tool with a deeply nested schema and an existing output schema, the description covers purpose, prerequisite ordering, and the no-write fallback path. What remains thin — platform-specific access requirements and what the returned download/link looks like in practice — is partly covered by the output schema and the plan access rules it delegates to.

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?

Top-level schema coverage is low, but the description compensates by explaining the key semantic of the single request parameter: its plan field is the same object workbook_plan accepts, with platform derived from the outer request, and that blocks/requirements are the only source of SheetsFinance functions. The rest of the layout semantics (labels, inputs, assumptions, native formulas, referencing planned output ranges) is described at a level that meaningfully guides construction.

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 opens with a specific verb and resource ('Create a new SheetsFinance workbook file') and immediately names the two concrete artifacts produced: an Excel download or a Google Sheets copy link. It also distinguishes itself from the sibling workbook_plan by framing itself as the executor of that plan.

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?

It gives a clear prerequisite chain: use model_catalog and get_model first when a published model fits, and pass the workbook_plan request as plan. It does not explicitly state the inverse case (e.g. when to call workbook_plan alone or when not to create a workbook), so the routing guidance is one-directional rather than complete.

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