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

Annotations declare destructiveHint=true and readOnlyHint=false, so the safety profile is already carried; the description still adds real behavior beyond that: case-insensitive duplicate detection returns exists=true, and created=true is only reported after a second read confirms the folder. It also discloses the OAuth scope and the consent_required failure mode for older connections. Minor gap: no note on whether annotation destructiveHint applies to folder creation or what happens on partial failure.

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?

Front-loaded with the use case and alternative, and every sentence carries information (semantics, idempotency, verification, permissions). It is a dense single paragraph of chained clauses, slightly harder to scan than a structured layout, but no sentence is filler.

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 4 params and an output schema present, the description covers trigger, parent syntax, dedupe/verification return semantics, permission requirement and the sibling alternative. Nothing an agent needs to call it correctly is missing; return-value detail is delegated appropriately to the output schema.

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 100%, so the baseline is 3, but the description adds meaning beyond the schema: the parent parameter is a dedupe key (same parent + case-insensitive name yields exists=true rather than a new folder), which no schema field states. Optional-vs-required semantics for parent are also clarified in prose.

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?

States a specific verb and resource (create a mail folder) in a specific backend (Exchange/Microsoft 365), and explicitly contrasts with create_email_folder for the Mac Mail app and references m365_list_email_folders for parent lookup. The agent can distinguish it from all siblings without opening a schema.

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?

Gives an explicit trigger ("when the user wants a new mail folder in their Microsoft 365 / Outlook account") and an explicit alternative with its condition ("For a folder of an account in the Mac's Mail app, use create_email_folder"). Prerequisite handling is also spelled out via the Mail.ReadWrite / consent_required note.

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