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

No annotations are provided, so the description carries the full burden. It usefully discloses the sort order and that each entry includes a message count, but says nothing about pagination behavior, authentication requirements, or rate limits for what is clearly a paginated list endpoint.

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?

A single, tightly written sentence that front-loads the action and resource, then adds the two most decision-relevant details (ordering and per-item message count). No filler.

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 read-only list tool with three optional parameters and no output schema, the description covers the essentials of what is returned and in what order. The main omission is any note on pagination defaults or how to page through results, though the schema partly covers that.

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%, so the page, limit, and status parameters are already documented in the schema (including the status enum and the limit max of 100). The description adds nothing about parameter usage, so the baseline 3 applies.

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 and resource ('List your virtual numbers') and adds the ordering ('newest first') and payload detail ('message count each'), which clearly separates it from the singular get_virtual_number sibling. It stops short of naming the alternatives it is not, so it is clear but not explicitly differentiated.

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?

There is no when-to-use or when-not-to-use guidance, no mention of prerequisites, and no pointer to alternatives such as get_virtual_number for a single number or list_number_countries. The listing intent is implied only by the verb.

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