Stop an in-progress call (requires confirm)

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

Annotations already declare destructiveHint=true and openWorldHint=true, and the description adds a genuinely non-derivable behavioral gate: the confirm:true requirement. That is the key operational fact for this tool. It still does not state whether the cancellation is irreversible or what happens to an already-connected call.

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 short sentences with zero filler; the action and the mandatory confirm gate are both front-loaded. Nothing redundant.

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, scope, and the confirm requirement, but omits what happens on success/failure and leaves callId semantics undefined. Adequate but with a visible gap.

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%, so the description must compensate. It clarifies the purpose of confirm, but callId — the only required parameter — is left entirely unexplained beyond the obvious. Roughly half the parameter surface is covered.

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 action pair ('hang up / cancel') plus the resource and the eligible states ('queued or in-progress call'), which clearly separates it from place_call. However it does not explicitly name a sibling or clarify how it relates to get_call/list_calls beyond the implied scope.

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 one concrete precondition ('Requires confirm:true'), which is actionable context, but offers no when-to-use/when-not guidance relative to alternatives such as prepare_call or place_call. Usage is implied by the stated call-state scope only.

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