start_outbound_call

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

Annotations already declare openWorldHint=true and idempotentHint=false, but the description adds real value by disclosing that this places a REAL call that 'bills voice minutes' — a cost/side-effect fact not in the annotations. It stops short of detailing rate limits or failure behavior, so not 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?

Three tight sentences with the core action and cost front-loaded, then safety/confirmation, then the bulk-use alternative. 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 7-param mutation with nested options/leadInfo and no output schema, the description covers the essential action, cost, confirmation, and alternative routing. It could mention what the call returns (call/conversation id) but is otherwise sufficient to invoke correctly.

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 86%, so the schema already documents to/from/mode/options/leadInfo/campaignId, including E.164 format and defaults. The description only reinforces the 'to' semantics from its 'calls the "to" number from its assigned number' phrasing, adding little beyond the schema — baseline 3.

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 a REAL outbound phone call') and clarifies the actor/callee mechanics ('the agent calls the "to" number... and talks to whoever answers'). This clearly distinguishes it from soft alternatives like contact_leads and campaign tools.

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 to confirm the number with the user first and routes high-volume use to contact_leads or campaigns_write. Both the when-to-use and the when-to-use-something-else are named with the alternative tool.

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