mailbox_whoami

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

With no annotations, the description carries the behavioral burden. 'List' strongly implies a read-only operation with no side effects, and the description states what information is returned. However, it does not clarify whether registration is required beforehand, whether the output is a simple array or structured object, or whether any permissions are needed.

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 a single sentence that says exactly what the tool does with no filler or repetition. Every word contributes meaning, and the main action and result are front-loaded.

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 zero-parameter introspection tool with no output schema, the description is largely sufficient: it names the two outputs (registered agents and mail root location). It loses one point because it does not specify the output shape or indicate whether mailbox registration is a prerequisite for appearing in the list.

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?

This tool has zero parameters, so there is nothing meaningful for the description to explain. The schema already covers the parameter surface completely, and the description appropriately focuses on the operation's outcome.

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 uses a specific verb ('List') and resource ('all registered agents and the mail root location'), making the tool's purpose immediately clear. This also distinguishes it from its siblings, which are all mailbox operations rather than agent-registry introspection.

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 no guidance about when to use this tool versus alternatives such as mailbox_list or mailbox_register. It does not mention prerequisites, typical use cases, or exclusions, so the agent must infer context from the name and siblings.

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