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

Adds substantial context beyond the annotations: a real human is rung, the call is irreversible in the real world but writes nothing to the row, DNC and legal calling hours still apply, and the call self-terminates after 3 minutes. This explains why destructiveHint=true on a tool that mutates no stored data — the destruction is a live outbound call — which is exactly the clarification an agent needs.

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-loads the core action and is dense with useful constraints; nearly every clause carries information. It is a single long sentence chain, so a small amount of structural separation would aid scanning, but there is no 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 3-parameter mutation-with-real-world-effect tool, the description covers the action, eligibility constraints, side effects on data, legal/compliance behavior, and duration limit. No output schema exists and none is needed, since the described outcome is a single phone call with no returned data to explain.

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 earns more: it explains that row is 1-based in upload order, that selecting a row makes the call use that contact's variables, and that nothing is persisted to that row — semantics the schema only partially conveys. The phone parameter's constraint is reinforced and paired with the practical guidance to ask the user which test number to use.

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 ONE real test call from the campaign's AI agent to a test number' — and pins the scope ('ONE', 'test number', 'Only AI campaigns'). This clearly separates it from launch_voice_campaign or update_voice_campaign, which an agent could otherwise confuse it with.

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 clear usage context ('before launching') and an operational instruction ('ask which one to use') together with a hard exclusion: only the account's saved test numbers can be dialed, and only AI campaigns are eligible. It stops short of naming the sibling tool (launch_voice_campaign) as the alternative, so the routing is implied rather than explicit.

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