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

There are no annotations, so the description carries the full burden of disclosing side effects and requirements. It does disclose the primary creation behavior and the nesting semantics, but it doesn't mention permissions, duplicate behavior, whether the operation is reversible, or what the response looks like. For a mutation tool, these are meaningful omissions.

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 sentences with no filler. The core action comes first, and the optional-parameter behavior follows immediately. Every word contributes to usability.

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 relatively simple, but with no annotations and no output schema, the description should clarify more than it does. It covers the creation action and the key optional param, but it leaves out return value, error-prone input expectations, and any distinction between folder types or services when similar mail-related tools exist.

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 only 33%, so the description must compensate. It adds useful semantics for parentFolderId, explaining that omitting it creates a top-level folder. However, it doesn't clarify the meaning of displayName or how mailbox maps to folder scope beyond what the schema already provides.

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 and resource: 'Create a mail folder.' It distinguishes itself from siblings like create_gmail_label or create_inbox_rule by focusing specifically on folders, and the nesting instruction adds scope clarity. It doesn't explicitly contrast with alternatives, but the core purpose is unambiguous.

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 one concrete usage rule: pass parentFolderId to nest, omit for a top-level folder. However, it doesn't explain when to choose this tool over alternatives such as create_gmail_label or create_inbox_rule. The guidance is implied by the tool name rather than explicitly stated.

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