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

Annotations only declare the coarse profile (not read-only, not idempotent, open-world), while the description supplies the real behavior: the request is relayed through the voice agent to the callee, the extension is conditional on consent, it is allowed once per question, seconds_left grows by 60, and total wait per question is capped at 2 minutes. It also discloses the failure/branch outcomes (accepted, callee_prefers_callback, not_possible) and that a callback reschedules when the answer is delivered.

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?

Front-loaded with the purpose, then trigger, then mechanics, then exclusions — a sensible order. It is somewhat long and repeats the relay idea ('the request is passed to the voice agent, which asks the callee' then later quoting the agent's phrasing), but almost every sentence carries operational detail.

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 annotations and an output schema, the description covers trigger, sequencing, consent semantics, the size and limit of the extension, and the follow-up event to look for. Nothing an agent needs in order to call it correctly at the right moment 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 the baseline is 3, but the description adds that call_id must reference a live call whose agent is waiting and that question_id ties the hold to a single pending_question from get_call (hence the once-per-question limit). Those constraints on valid values go slightly beyond the schema text.

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 names the specific action (extend the answer window by one minute) applied to the specific resource (the voice agent's pending question on a live call), and distinguishes it from answer_call_question and get_call by role in the workflow. An agent can tell from the first sentence alone what this does and what it does not do.

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 gives a concrete trigger ('as soon as get_call shows a pending_question you cannot answer yourself'), an explicit sequence (call hold_call_question first, then ask your human, then answer_call_question), and negative cases ('not for a finished call, nor when you already know the answer — just answer'). The alternative path when the callee prefers a callback is also spelled out.

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