Set when the broadcast starts

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

With no annotations, the description carries the full burden and does disclose the user-facing effect (viewers see a countdown and calendar link), the clear/reset semantics, and a prerequisite state (booth must be open). It does not cover permission requirements, idempotency, or what happens if the start time is set after go_live.

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?

Two short sentences, front-loaded with the primary effect, then the clearing behavior and precondition. No filler sentences.

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 tool with full schema coverage and no output schema, the description supplies what structured fields cannot: viewer-visible consequences and the booth prerequisite. The only real gap is the timezone argument's interaction with the start string, which the schema largely handles.

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 explains start, timezone and meeting_id in detail. The description's "empty start to clear it" merely restates the schema's "or empty to clear" and says nothing about the timezone parameter — 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?

States a specific verb and resource (set the start time) plus the exact viewer-visible outcome: a countdown and Add to calendar entry. That scoping distinguishes it from scheduling siblings like schedule_meeting, though no sibling is named explicitly.

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 concrete precondition ("Needs the open booth") and an explicit alternate use ("Pass an empty start to clear it"), so an agent knows the context for calling it. It stops short of naming when to prefer a different tool or what to do if the broadcast is already live.

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