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

The description clearly describes a write/mutation action that creates a campaign and starts dialing places calls, while annotations declare readOnlyHint=true and idempotentHint=true. This is a direct contradiction: a tool that 'begins dialing on its own' is not a read-only, idempotent operation. Flagged as an annotation contradiction, so the score is capped at 1.

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, front-loaded with the core action. The trailing clause 'It begins dialing on its own — no separate start' earns its place by preempting a likely follow-up question. 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 10-parameter mutation tool with full schema coverage and no output schema, the description covers purpose and key runtime behavior (auto-dial, retries, concurrency). It omits permission/auth requirements and any note about phone-number validation or failure handling, leaving modest gaps given the tool's complexity.

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 description coverage is 100%, so the schema already documents all ten parameters (name, phone_numbers, agent_id, max_concurrent, max_attempts, etc.). The description restates a few of them (list of numbers, voice agent, bounded concurrency, retrying no-answers) but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 a specific verb and resource ('Start a bulk outbound call campaign') and specifies scope precisely: dialing a list of numbers with a voice agent at bounded concurrency, phone-network only. An agent can immediately tell this apart from single-call siblings like calls_make and from campaigns_pause/resume/status.

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 implies usage context ('Phone network only (twilio/telnyx)', 'begins dialing on its own') but never states when to use this versus alternatives such as calls_make for a single call, or the sibling campaign lifecycle tools. Usage is implied rather than explicit, and no when-not guidance is given.

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