Fire an event

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

Annotations already declare readOnlyHint=false, idempotentHint=false, openWorldHint=true, so the agent knows this is a non-idempotent, side-effecting call. The description adds that the event is observable by automations, but says nothing about persistence, whether the event is transient, or permissions required.

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?

Short, but it repeats the 'Args:' prefix in two consecutive sentences, which is wasted space in an otherwise tiny description and creates mild redundancy.

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 simple two-parameter fire-and-forget tool with no output schema and annotations covering the safety profile, the description is nearly sufficient. Only a note on event persistence/delivery behavior is missing.

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 both parameters are already documented. The description adds only an example value ('my_custom_event') and restates that eventData is an optional JSON object — marginal value 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+resource ('Fire a custom event on the event bus') with the key consequence that automations can listen for it, which separates it from ha_call_service and ha_set_state. It does not explicitly name a sibling, so it stops short of 5.

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?

The parenthetical 'automations can listen for it' implies the scenario where this tool is appropriate, but there is no explicit when-to-use, no exclusion, and no pointer to alternatives such as ha_call_service for triggering actions.

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