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

Annotations already flag this as destructive, open-world and non-idempotent, yet the description still adds substantial operational context: the AI disclosure is always made, per-number anti-harassment limits, a simultaneous-call limit with queueing, refusal when exceeding the 24-hour quota, retry and 15-minute-wait behavior inside the 08:00-21:00 window, and per-call billing. What it does not clarify is the partial-failure semantics of a batch beyond pointing to a 'refused' list, which keeps it from a 5.

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?

Purpose and return value are front-loaded, and nearly every sentence carries operational fact rather than filler. The compliance and timing sentences are dense and slightly run-on (the 15-minute/08:00-21:00 clause is hard to parse on first read), which costs a point but does not obscure the core instruction.

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 high-stakes bulk outbound-calling tool with six parameters and an output schema, the definition covers purpose, legality, quota and concurrency behavior, billing, return handling and plan gating. Since an output schema exists, the description need not enumerate return fields, and nothing an agent needs in order to call this safely 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 genuinely adds meaning: task must mirror place_phone_call and never be marketing, phone_numbers are French-only, capped at 100, echoed as given, and duplicates/invalid entries are skipped and returned in 'refused'. That last point is behavioral detail the schema does not convey.

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 ('Place the same call to a list of numbers in France') and immediately discloses the return shape (batch_id plus one call_id per number). It also distinguishes itself from the sibling place_phone_call by describing itself as the same task applied to many numbers, so an agent can choose between them without inspecting schemas.

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 explicit triggering conditions ('when the user explicitly asks to make the same kind of call to several numbers they provide') with two concrete examples, plus exclusion rules (marketing, prospecting, surveys, mass calling refused) and a recovery path for non-Pro accounts (plan_feature_required). It also names the follow-up tools, get_batch_calls and get_call, closing the loop on what to do next.

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