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

With no annotations, the description carries the full behavioral disclosure burden. It communicates that this is a read-only listing operation, scoped to the authenticated account and outbound messages, and that it returns recent items. It does not disclose pagination behavior, ordering details, or possible response/error characteristics, which are not covered elsewhere.

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 front-loads the core action and resource, followed by scope and filter availability. There is no redundant wording or unnecessary detail.

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 low-complexity list tool, the description plus the fully documented schema provides enough context to invoke the tool correctly: it identifies the resource type, scope, recency, and filter capability. However, absent annotations and an output schema, a bit more detail about ordering or response shape would make it fully complete.

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 input schema already documents all three parameters with descriptions and enums, achieving 100% coverage. The description only adds the generic phrase 'optional filters,' which correctly signals that all parameters are optional but adds no specific semantic detail beyond the schema.

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 action and resource: 'List recent outbound messages'. It also specifies scope ('for the authenticated account') and the presence of optional filters, which differentiates it from siblings like send_sms, get_message_status, and list_campaigns.

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 when to use this tool—when a list of recent outbound messages is needed—but it does not explicitly contrast it with alternatives such as get_message_status for a single message or list_campaigns for campaign-level data. No exclusions or when-not-to-use guidance is provided.

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