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

Annotations cover the safety profile (destructiveHint=true, readOnlyHint=false, idempotentHint=false), so the bar is lower. The description adds real value by disclosing that live provider ordering and assignment require operator approval - key context about the deferred/asynchronous nature of the operation. It does not, however, explain what 'managed' entails or any auth/cost constraints.

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 front-loaded sentence with the action verb first and zero filler. It is efficient, though its brevity is also the source of the coverage gaps noted elsewhere rather than a model of completeness.

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 an 11-parameter, non-idempotent, destructive mutation with no output schema and 18% schema coverage, the description is far too thin. It leaves the meaning of most parameters, permission requirements, and the request lifecycle unexplained.

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 only 18%, with 9 of 11 parameters undocumented, so the description must compensate - and it does not mention a single parameter. Fields like customer_type, number_type, requested_capabilities, and customer_reference carry domain-specific meaning the agent has no way to resolve from the description.

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?

States a specific verb+resource: 'Create a managed phone-number request.' The word 'managed' usefully signals this is a request workflow rather than direct provisioning, which separates it from siblings like list_numbers or get_number_catalog. However, it names no sibling explicitly, so differentiation is only implicit.

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 clause about operator approval implies the tool is for initiating a request that will not immediately complete. But it gives no explicit when-to-use guidance versus alternatives such as check_number_requirements or get_number_catalog, nor any prerequisites. Usage is only implied.

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