get_messages

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

There are no annotations, so the description carries the behavioral burden. It communicates a read-only list operation and states the return fields, which is meaningful. However, it does not disclose side effects, pagination, empty-result behavior, or how it handles invalid addresses.

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?

One sentence with the action and resource front-loaded, followed by the return format. No redundant or filler content.

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 simple one-parameter list tool with a clear output description, the definition is mostly complete. It lacks explicit sibling differentiation and minor edge-behavior details, but those are not critical for basic invocation.

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?

The single parameter address is already fully described in the schema, and the tool description adds no extra meaning beyond implying it identifies the mailbox to check. Baseline 3 is appropriate because schema coverage is 100%.

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 clear operation: 'Get the list of received emails' for a temporary mailbox, and specifies the output content (message summaries with ID, from, subject, date). It is distinguishable from the sibling get_message by the word 'list' and 'summaries', though it does not explicitly name or contrast that sibling.

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 gives no explicit guidance about when to use get_messages versus siblings like get_message, wait_for_email, or get_verification_code. The only usage signal is implicit: this tool returns summaries rather than full message details.

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