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

Annotations already declare destructive=false? No – destructiveHint=true, openWorldHint=true, idempotentHint=true, readOnlyHint=false, and the description adds real value on top: the answer is spoken aloud to the person on the phone (explaining the real-world, non-read-only effect) and a question that already expired or was answered returns delivered=false and is safe to retry (consistent with idempotentHint). It stops short of stating auth or permission requirements.

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?

The first sentence front-loads verb, resource, and required identifiers; the retry/return-value note at the end is actionable. The middle sentences are somewhat convoluted and could be tightened, but nothing is pure filler.

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 three-parameter mutation tool with no output schema, the description covers the call context, the required request_id, the provenance of the answer text, and the delivered=false failure mode. It is close to self-sufficient, missing only permission/ownership requirements for whose answer may be delivered.

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 0%, so the description must compensate, and it does: request_id is explained as naming which question is being answered when several are pending, and answer is constrained to the account holder's own words and facts supplied by them. call_id is only implicitly explained as the call identifier, leaving a small gap.

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 (deliver the account holder's answer) and resource (a question an in-progress call is waiting on), and pins the identity to call_id + request_id sourced from get_call_result. An agent can distinguish this from get_call_result, place_call, and suggest_places without opening any 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?

Explicitly says when to call (a call is waiting on a question) and names get_call_result as the origin of request_id, plus a when-not: if the account holder hasn't supplied an answer, the question is theirs to see rather than something to compose. It doesn't explicitly rule sibling tools in or out, but the operational context is clear.

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