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

The description is otherwise unusually rich - it discloses that the tool returns immediately, never reports the call as ended, that the media worker tears the call down, and that the call reaches its terminal event via the ordinary path. However, it states 'Repeating the request is idempotent and returns the original timestamp', which directly conflicts with the annotation idempotentHint=false. That inconsistency is a serious behavioral disclosure problem even though the destructive/openWorld hints are consistent with the described teardown.

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, front-loaded with the action, then the return/async contract, then idempotency and the refusal condition. No sentence is padding.

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?

With no output schema, the description supplies the return value (hangup_requested_at), the asynchronous teardown path, the terminal-event behavior, and the refusal case. An agent has everything needed to call it and interpret the result, aside from the idempotency inconsistency.

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 0% for the single call_id parameter, so the description carries the burden. It does add meaning by stating the referenced call must be live and not merely queued for origination, but it never says what form call_id takes or where to obtain it, leaving part of the semantics implicit.

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 ('ask a call that is already live to hang up') and immediately bounds the scope to live calls, distinguishing it from get_call, create_outbound_call, and the campaign control tools. An agent can identify the operation without opening the schema.

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 applicability condition (the call must already be live) and an explicit exclusion ('a call still queued for origination is refused'), plus the repeat-call behavior. It does not name a sibling alternative for the queued case (e.g. cancel_campaign), so it stops just short of full routing guidance.

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