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

Annotations do not include readOnlyHint or destructiveHint. The description implies a read-only query but does not explicitly state that it has no side effects, how the data is sourced, or whether the quota is real-time. No behavioral context is added beyond the bare enumeration of data.

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 concise in length but poorly structured. It is a grammatically awkward fragment that lists items without a clear subject-verb beginning, reducing front-loading and readability.

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?

With no output schema, the description must convey what the tool returns. It lists three pieces of information but with ambiguous phrasing (e.g., 'The number texts are sent from') and does not specify the response format or whether these are separate fields or a combined result. The description is not self-sufficient.

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 tool has zero parameters and the schema is empty with 100% coverage, so the baseline is 4. The description does not need to explain parameters; it provides no additional parameter-related meaning but is not deficient.

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 conveys that the tool provides information about the sender number, verified numbers, and remaining message quota. This distinguishes it from sms_send, sms_verify, and sms_history. However, it lacks a clear imperative verb and reads as a fragment.

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?

No guidance is provided on when to use this tool versus the sibling tools. It does not state use cases, prerequisites, or exclusions, leaving the agent to infer when this tool is appropriate.

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