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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds ordering (newest first) and pagination behavior plus the returned field set, which annotations do not convey, but it omits how pagination terminates (no total or next-page indicator).

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?

Two sentences, zero filler, with the resource, returned fields, ordering, and pagination front-loaded before the practical Drafts hint. Every clause earns its place.

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 correctly carries the return-value burden by listing the summary fields, and it covers ordering and pagination. It could be slightly more complete about how paging interacts with the page/limit parameters, but for a read-only listing tool it is largely sufficient.

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%, so all five parameters including defaults, the 1-based page, and the 100 max limit are documented in the schema. The description only reinforces the folder semantics with the Drafts example, adding little beyond the schema's 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 (message summaries) and enumerates the returned fields (sender, subject, date, snippet, uid, labels), giving the agent a precise picture. It does not, however, differentiate itself from the sibling search_messages, leaving that distinction implicit.

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 only usage guidance is the concrete tip that folder "Drafts" surfaces saved drafts. There is no statement of when to prefer this listing tool over search_messages or search_all_mailboxes, and no exclusions, so usage is largely implied.

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