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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the bar is lower. The description adds the exactness and ID-resolution constraint, but doesn't describe error behavior or return shape, which matters because there is no output schema.

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 short and front-loads the core purpose, then gives the resolve-first rule and the 'never pass a human folder name' caution. It has some redundancy with the schema, but every sentence still contributes actionable guidance; the missing punctuation after 'folder.id' is a minor readability flaw.

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 two-parameter read operation, the description plus schema and annotations cover the required folder_id format, where to obtain it, and the optional account_id selection rule. There is no output schema, so a brief note on return value or not-found behavior would make it fully complete.

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 description coverage is 100% and the description largely repeats the folder_id schema text ('Exact Gmail label... Obtain with email_list_folders -> folder.id'). It therefore doesn't add meaning beyond what the input schema already provides, so the baseline of 3 is appropriate.

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?

Description uses a specific verb ('Get') and a clearly bounded resource ('one exact Gmail/Outlook/IMAP folder'), immediately distinguishing it from listing or resolving folder operations such as email_list_folders and email_resolve_folder.

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 explicitly instructs the agent to resolve a folder name to an ID first and to obtain that ID via email_list_folders, and it warns never to pass human folder names like 'Inbox'. It doesn't explicitly contrast this tool with the resolve/list siblings, so it stops short of a full 5.

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