List unread mailbox messages

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description adds value by clarifying that messages are not claimed or changed, which is operationally meaningful beyond generic read-only, and by narrowing scope to unread messages in a single mailbox. It does not contradict the annotations.

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?

A single, tightly scoped sentence with no filler. It front-loads the action and resource, then adds the crucial no-side-effect qualifier, making every word earn its place.

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 output schema, annotations, and schema-described parameters, the description is nearly complete for a simple read-only listing tool. The only real gap is explicit alternative-tool routing, which is a usage-guidelines deficit rather than a completeness failure for invoking the tool correctly.

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 67%: mailbox_id and response_format are already documented in the schema, and limit has clear type/default/min/max constraints. The description adds no per-parameter detail beyond 'one registered mailbox', reinforcing mailbox_id but not explaining limit or response format further. This is acceptable but not additive.

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 states a specific verb ('List'), a clear resource ('unread messages in one registered PromptJang mailbox'), and an explicit non-side-effect scope ('without claiming or changing them'). This distinguishes it from siblings like claim_message and ack_message, and from get_message, which targets a single 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 implies usage for read-only enumeration of unread messages and explicitly says it does not claim or change messages, which helps rule out claim/ack tools. However, it does not explicitly state when to use this versus list_mailboxes or get_message, or name alternative tools for those cases.

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