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

Discloses traits the annotations cannot express: sends are near-instant, irreversible, partially complete on cancellation ('emails already handed over still go'), and fail at the first readiness problem. This is exactly the operational context an agent needs before invoking an irreversible outward-facing action; note the mild tension with destructiveHint=false, though that hint concerns data destruction rather than external side effects.

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 irreversible warning in the first sentence and then enumerates transitions compactly, with no wasted preamble. The prose is densely compressed with colon-joined clauses, which costs a little readability but no substance.

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 tool with no output schema, it covers prerequisites, failure behavior, irreversibility, and cancellation semantics. The only real gap is what the call returns or how the resulting broadcast state should be verified afterward.

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 only 33% (scheduled_for is the sole documented property), and the description compensates by explaining what each status value does and that scheduled_for must be a future time, with null otherwise. broadcast_id is left self-evident, and no epoch-format detail is repeated beyond the schema.

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 plus the full domain of state transitions: 'sending' dispatches email, 'scheduled' targets a future time, 'draft' unschedules, 'canceled' stops an in-flight send. An agent can distinguish this from update_broadcast/delete_broadcast because the description frames it purely as lifecycle movement.

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 a strong precondition — 'only call it after the user has seen the email and the audience and said yes' — and routes pre-flight validation to get_broadcast_readiness, which clearly tells the agent what to call first. It does not explicitly say when to prefer this over update_broadcast or delete_broadcast, so sibling selection is only partially covered.

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