message_inbox

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe read operation. The description adds key behavioral context: messages stay unread until mark_read is called, which is safe for concurrent agents. It also discloses deprecation status. This adds value beyond annotations but does not describe the return format or ordering. With annotations covering safety, a 3 is appropriate.

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 structured with a deprecation notice, a usage instruction, and an explanation of read semantics. It is reasonably concise, but the deprecation notice could be seen as extra fluff. Still, it earns its place by preventing misuse.

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?

For a no-parameter read tool with an output schema, the description is largely complete. It covers when to call, how to handle messages, and its deprecation status. The main missing element is what the output looks like, but the output schema can cover that. It does not mention any edge cases (e.g., no unread messages), but these are minor given the annotations.

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?

There are no parameters, and the schema coverage is 100% (since there are none). The description does not need to explain parameters. Baseline 3 is fine because there is nothing to add.

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 the tool reads unread messages, a specific and actionable purpose. It is distinguished from siblings like message_list (which likely lists all messages) and message_mark_read (which marks messages as read). However, the deprecation notice adds some ambiguity about its current role, slightly reducing clarity.

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 explicit usage guidance: 'Call this at session start.' It also explains when to use message_mark_read: 'once you've processed a message.' It does not explicitly list alternatives, but the deprecation notice makes it clear that this tool is not for new work, implying alternatives exist. This is good but not perfect.

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