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

With no annotations, the description carries the full burden, but the verb 'List' clearly signals a read-only operation and the description adds context about ANRT validation and account scoping. However, it doesn't disclose pagination behavior, ordering, or the fact that the filter actually supports rejected and all statuses — the description only mentions approved and pending.

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 short and front-loaded with the core listing behavior, and the status-filter context appears early. The bilingual duplication (French + English restating the same thing) is a minor inefficiency, but overall every sentence earns 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?

For a simple, single-parameter list tool with no output schema, the description is adequate: it names the resource, the scoping, and the status dimension. It doesn't specify return-value shape, but for a straightforward list whose parameter is fully documented, that is an acceptable gap.

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 100% and the single status parameter is fully documented with an enum and default value. The description adds the 'approved and pending' phrasing, which partially maps to the enum, but it contributes little beyond the schema — baseline 3 is appropriate.

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') and resource ('custom alphanumeric Sender IDs') scoped to the authenticated account, and it clearly distinguishes from siblings like list_campaigns, list_messages, and list_contacts. The French opening adds the ANRT-validation context that reinforces the tool's purpose.

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 scope ('registered on the authenticated account') gives clear context for when this tool applies, and no close sibling provides a competing Sender ID-listing operation, so no exclusion is strictly needed. It doesn't explicitly state 'use this when you need to see your sender IDs,' but the context is clear enough.

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