Fire a Home Assistant event

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

Annotations (readOnlyHint=false, destructiveHint=true, openWorldHint=true, idempotentHint=false) already carry the safety profile, so the bar is lower. The description still adds real value by disclosing the POST endpoint, that effects are listener-dependent, and that a confirmation dict is returned.

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 core action, then gives mechanism, usage condition, and return in labeled, scannable lines with no filler. Slightly longer than strictly necessary given the schema already documents the parameters, but nothing is wasted.

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?

Given annotations cover the mutation/safety profile and an output schema exists (so return values need not be explained), the description covers the key non-obvious behavior: effects depend on registered listeners. Only minor gaps remain, such as permission requirements or restart/persistence implications.

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 (event_type, event_data) are already fully documented in the schema, and the description largely restates them ('event_data as the JSON body'). Baseline 3 is appropriate since the schema does the heavy lifting.

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 an arbitrary Home Assistant event') and even names the underlying REST endpoint and payload mapping. An agent can distinguish this from siblings such as services_call_service or automations_trigger_automation because it targets raw event firing rather than named services/automations.

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 'Use when: triggering automations or integrations that listen for a specific event type' line gives clear positive guidance, and the note that effect depends on what is registered adds useful scoping. It does not, however, contrast itself with alternatives like calling a service or triggering an automation directly, so routing among siblings still requires inference.

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