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

Annotations already flag destructiveHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds real value by describing the resulting state change (calls display the KaiCalls line again) and the owner-only permission requirement, which annotations do not convey.

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?

Two compact clauses, effect first, constraint second, with no wasted words. Slightly informal phrasing ('the person's own number') but still unambiguous.

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?

An output schema exists, so return values need no explanation, and for a one-parameter reversal tool the description covers effect and authorization adequately. The only shortfall is the unexplained business_id argument.

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 single business_id parameter has 0% schema description coverage and is not required, and the description never mentions it. With low coverage the description should compensate but does not, leaving the parameter's meaning entirely undocumented.

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 gives a specific verb+resource pair: stop displaying the person's own number so calls revert to the KaiCalls line. That distinguishes it from get_own_caller_id and start_own_caller_id by implication, though no sibling is named explicitly.

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?

It states the operational condition (calls should show the KaiCalls line again) and an authorization constraint ('Business owner only'), which is genuine usage guidance. However, it never names the counterpart tool or says what to use if the caller ID was never enabled.

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