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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, covering the safety profile. The description adds the cost per call ($0.005), which is valuable behavioral context not present in annotations. It doesn't contradict the annotations and provides additional transparency about the financial implication.

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, front-loaded sentence that includes the cost, the action, and the resource. There is zero wasted verbiage, and the most critical information (cost) appears first. This is an ideal example of concise, efficient tool documentation.

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 listing tool with no output schema, the description covers the core purpose and cost. It doesn't mention the return format or potential pagination, but given the tool's trivial nature and the read-only, idempotent annotations, these are not critical gaps. The payment parameter workflow is documented in the schema, so the description is sufficiently complete for an agent to use it correctly.

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 schema description coverage is 100%, with the single optional 'payment' parameter fully documented in the input schema. The tool description adds no additional meaning about parameters; it only mentions the cost, which is not parameter-related. Baseline 3 is appropriate since the schema already handles parameter documentation.

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 clearly states the action ('List') and the resource ('registered model providers in the Sovereign Router pool'), which is specific and unambiguous. It doesn't explicitly differentiate from siblings, but the resource name is distinct enough that an agent would not confuse it with the other listed tools like 'route' or 'score'.

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 usage (to list providers) but provides no guidance on when to use this tool versus alternatives or when not to use it. There are no explicit exclusions or prerequisites. Given the tool's simplicity, this is acceptable but not exemplary.

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