sch_list_mail

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

With no annotations, the description carries the full burden and does add real behavioral context: the 'id' is an IMAP UID that is stable across calls (unlike a sequence number) and is the value every msg_id parameter expects, plus which credentials file/account governs the call. It omits rate limits, ordering guarantees, or empty-result behavior, but the UID stability note is genuinely useful information not available elsewhere.

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 primary action is front-loaded in sentence one, the important UID caveat follows, and the Args block is a compact per-parameter reference. No sentence is redundant or padded.

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 read-only listing tool with an output schema present, the description need not explain return shape, and it correctly focuses on parameters and the id semantics that link output to other tools. Minor gaps remain (no statement about empty results or what happens if the folder is missing), but nothing essential for a correct call is absent.

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 0%, so the description must compensate, and it does for all four parameters: folder default INBOX, top default 20 with a 100 maximum, the YYYY-MM-DD format and 30-day default for since, and the account key convention with its default resolution rule. This is exactly the information the bare schema lacks.

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?

The first sentence gives a specific verb and resource ('List recent messages') plus the concrete fields returned (subject, sender, date, attachment indicators), which distinguishes it from sch_get_mail and sch_search_mail implicitly. It never names the alternatives, so an agent must infer the routing, but the purpose itself 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?

The default 30-day 'since' window and 'recent messages' framing imply when this listing tool is appropriate versus a search, but there is no explicit when-to-use or when-not-to-use statement and no sibling is named. Guidance is implied rather than stated.

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