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

Annotations already declare read-only, idempotent, non-destructive behavior. The description adds real value beyond that: auth gating (owner/admin keys), default ordering (newest first), the returned field set, and the pagination contract (nextCursor passed back verbatim with the same filters).

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 compact sentences, front-loaded with the mailbox scope and key facts. No wasted words; the ordering and pagination notes are placed sensibly. Slightly dense but efficient.

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?

With no output schema, the description helpfully enumerates returned fields (id, threadId, from, subject, snippet, date, folder, read flag) and covers auth, ordering, and pagination. Adequate for an 8-parameter list tool, though default folder/limit behavior is only in the 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 every parameter (limit, query, since, until, cursor, farmId, folder, unreadOnly) is already documented in the schema. The description's cursor note ('passed back verbatim with the same filters') mostly restates the schema, adding little beyond the baseline.

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 (List) and resource (messages in the QuailOS Email Assistant inbox), clearly distinguishing it from get_email, send_email, and move_email by the plural-list scope. It does not explicitly name a sibling it is not, but the verb+resource 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?

It states the access requirement (Owner/admin AI keys only) and ordering (newest first), which imply when it can be used. However, there is no explicit guidance on when to use this versus get_email for a single message or draft_email_reply for responding, leaving routing to inference.

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