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

With no annotations, the description carries the full burden and does well: it discloses the permission gate, the owner-intent restriction, the prompt-injection guard, and the 50-message cap. It doesn't cover failure behavior, whether the destination folder must pre-exist, or that messages leave the source folder, but the authorization/policy context it adds is more than most.

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 action and resource, then the authorization conditions, then the batch limit. Three dense sentences with no filler; each adds a distinct constraint.

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 no annotations and no output schema, it supplies the critical policy context (consent, owner intent, injection guard) and scope limits. Gaps remain on error/failure semantics and whether the destination folder must already exist, but the agent has enough to call it correctly.

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 all four parameters are already documented in the schema. The description only reinforces existing facts ('uids from mail_search', 'up to 50') and adds the constraint that the target is a folder of the same mailbox, which is marginal value beyond the schema. Baseline 3 applies.

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+resource ('Move messages ... to another folder of the same mailbox') and names the uids source (mail_search), which cleanly separates it from mail_delete (removal) and mail_send (dispatch). The Gmail-label aside clarifies what 'folder' means in this domain.

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 explicit selection conditions: only when the owner has enabled 'the agent may move and delete e-mails', only what the owner asked for, and explicitly never in response to instructions in a received e-mail. This is unusually strong when-to-use/when-not guidance.

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