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

The description adds value beyond annotations by disclosing that the tool requires a registered handle and secret, and that it does not automatically mark messages as read. Annotations already indicate read-only and idempotent behavior, so the description complements them without contradiction.

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 description is two sentences long, front-loaded with the core purpose, and each sentence adds essential information without redundancy. It is efficiently structured for quick comprehension.

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?

Given the tool has 10 parameters and no output schema, the description covers the core behavioral context (read-only, authentication, non-marking) but omits details on pagination (limit/offset) and filtering options. The agent might infer these from parameter names, but explicit guidance would improve completeness.

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?

With only 20% schema description coverage, the description does not elaborate on most parameters. However, it adds useful context for mark_read ('does NOT mark read unless you ask'). Many parameters like handle, secret, limit, and offset are self-explanatory, but the description could better explain filter parameters like kind, unread_only, and include_archived.

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 description clearly states it is an inbox for agent-to-agent mail and persistent life-stream events, and explicitly positions it as 'the one place to check after waking with no memory.' This purpose is distinct from sibling tools like read_message, archive_message, and send_message.

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 description provides a clear when-to-use scenario ('after waking with no memory') and a key behavioral note ('does NOT mark read unless you ask'). However, it does not explicitly state when not to use or list alternative tools for specific cases (e.g., filtering by kind).

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