Hang up a call

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

Annotations already flag destructive=true, idempotent=true and readOnly=false, so safety is covered structurally. The description adds genuine extra behavior: a precheck that the call is live or queued on this account, and the call_not_active error result when the call already ended.

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 dense sentences: the action and endpoint come first, followed by the precheck, the required inputs, and the failure result. No filler or repetition.

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 two-parameter mutation with no output schema, the description covers the action, preconditions, required confirmation guardrail, and the one notable error return. Annotations handle the safety profile, so nothing an agent needs is missing.

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 call_uuid and confirm are already fully documented in the schema, including the same confirm-after-explicit-request wording. The description repeats rather than extends that meaning, so the baseline 3 applies.

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 (terminate) and resource (active or queued call) and even names the underlying endpoint. An agent can distinguish this from hangup_conference_member and end_conference, which act on conference participants or whole conferences.

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 a clear usage condition: confirm:true must be set only after the user explicitly asked to end this call, which is real routing/guardrail guidance. It stops short of naming alternatives (e.g. hangup_conference_member for conference members), so it lacks explicit when-not guidance.

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