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

readOnlyHint=true already declares the safety profile, and the description adds behavior beyond that: results are ordered newest-first, snippets are short previews rather than bodies, and pagination flows forward through a cursor. It does not state any auth/permission prerequisites, but for a read-only listing the disclosure is solid.

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?

Three tight sentences, front-loaded with what is returned, then filtering, then paging, then the escalation path to mAYL_view. No filler and no sentence that could be dropped without losing an instruction.

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 compensates by enumerating the returned fields and explaining the cursor round-trip. For a three-parameter, read-only list tool this covers everything an agent needs to call it correctly and to know when to escalate to mAYL_view.

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 the schema already documents all three parameters including the enum meaning of inbound/outbound and the next_cursor-to-before handoff. The description largely restates those semantics rather than adding new ones; the baseline 3 applies when the schema carries the load.

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 and resource ('List the user's mailbox'), defines the scope ('their <userId>@mosadd.com inbox/outbox', newest-first), and enumerates what comes back (sender, subject, status, snippet). It also explicitly distinguishes itself from mAYL_view, which reads a full body, so an agent can pick between the two without opening a schema.

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?

Gives concrete context: use the direction filter for received vs sent, omit it for both, and page older mail by passing next_cursor into `before`. It names the alternative for reading a full message (mAYL_view), but says nothing about other mail-adjacent siblings such as mAYL_agentbox_list or mAYL_events, nor when not to use this tool.

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