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

No annotations are provided, so the description carries the full burden. It discloses the auth requirement and the shape of the returned threads, and 'List' implies a read-only operation, but it stays silent on pagination/limits, ordering, and whether reads mark messages as seen.

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, front-loaded with the core action and scope, with the login caveat trailing. Nothing is padded and nothing needs trimming.

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 and no annotations, the description does a fair job by naming the fields an inbox listing returns. It still leaves pagination and result-set behavior unstated, which matters for an inbox that could be large.

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 coverage is 100% and the single parameter (notification_message) is fully documented in the schema itself. The description adds no meaning about that fallback-message parameter, so the baseline of 3 applies rather than a higher score.

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 signed-in user's Jiji message inbox') and even enumerates the content returned: threads with seller, advert title, last message preview. It does not explicitly distinguish itself from siblings like view_chat_thread or start_chat, but the scope 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 only guidance is the prerequisite 'Requires login'. It never says when to pick this over view_chat_thread (single thread) or whether it is for paginating, checking unread, or initiating a reply. Usage 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.