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

Annotations already mark it destructive and not read-only, but the description adds important behavior beyond them: it is a real action, not a preview, and the cancellation cannot be restored. It also prescribes a confirmation workflow, which is exactly the kind of context an agent needs for a destructive operation.

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?

Three tight sentences with no waste. The purpose and scope are front-loaded, followed by parameter sourcing and then the irreversible-action warning.

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 single-parameter destructive mutation with no output schema, the description covers the essential missing context: what it does, the prerequisite state, the irreversibility, and the required user confirmation. An agent has enough to call it correctly and safely.

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 coverage is 100%, so the parameter is already documented, but the description adds useful source context by naming getCallHistory and scheduleCall as origins for the call id. The schema's warning that it is a UUID rather than a phone number or name is also reinforced by the description's focus on call id.

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 and resource: cancel a scheduled outbound call that has not been placed yet. The scope condition clearly distinguishes it from scheduling or inspecting calls, and the required call id origin points to related tools.

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?

Gives clear context for when to use it: only for scheduled outbound calls not yet placed, and requires explicit user confirmation immediately before invocation. It does not explicitly name alternatives such as reporting an issue for already-placed calls, so it falls short of full when/when-not guidance.

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