list_phone_numbers

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

The description claims 'List all phone numbers' but the annotation openWorldHint=true indicates the result set may not be complete. This contradiction misleads the agent into assuming exhaustiveness. The description adds no other behavioral context beyond what annotations already provide.

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 immediately conveys the purpose with no extraneous words. It is front-loaded and efficient.

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?

Without considering the contradiction, the description is sufficient for a zero-parameter list tool with output schema present. However, the contradiction undermines completeness by providing false assurance of completeness. Also lacks mention of what fields are returned, though output schema may cover 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?

There are no parameters, and schema coverage is 100% (trivially). The description does not need to add parameter details. Baseline 4 applies per guidelines for zero parameters.

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 all phone numbers') and the resource ('associated with the ElevenLabs account'), making it distinct from sibling tools like list_agents or list_conversations. The verb and resource are specific and unambiguous.

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 on when to use this tool versus alternatives. However, given the simple nature (no parameters, clear listing), implicit usage is straightforward. A higher score would require explicit context or exclusions.

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