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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds real value beyond that: sort order ('newest first'), scope ('Owner-scoped'), and the exact result fields (address, display_name, kind, agent_id, expires_at) that stand in for the missing output schema. It stops short of any volume, pagination, or expiry-filtering behavior.

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 short sentences with zero filler, front-loaded with the action and object. The field list is parenthetical and the scope constraint is a terse trailing fragment, so every clause carries information.

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 parameters and no output schema, the description compensates by enumerating the returned fields and their ordering, which is the main thing an agent needs. It leaves open whether results are bounded or paginated and whether 'active' excludes anything, which are the only remaining gaps.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline applies. The description correctly omits any param discussion and instead spends its words on scope and return shape.

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?

Specific verb ('List') plus a specific resource ('your active agent inboxes') and the exact fields returned. An agent can distinguish it from mAYL_agentbox_provision/extend/release by the 'list' verb, but the description never names those siblings or the related mAYL_list tool, so differentiation is inferred rather than stated.

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?

Usage is only implied: 'your active agent inboxes' and 'Owner-scoped' suggest the call is for inspecting your own inboxes before acting on them. There is no explicit when-to-use, when-not-to-use, or routing statement pointing at a sibling such as mAYL_agentbox_extend or mAYL_agentbox_release.

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