Set a connected robot's status light to off, red, green, or blue so an AI agent can signal state through Reins with stale and replay checks.
Set the status light.
| Name | Required | Description | Default |
|---|---|---|---|
| color | Yes | ||
| issued_at | No | Optional. Unix time the command was issued; older than 5 s is refused as stale. | |
| request_id | No | Optional. A unique id; a repeated id is refused as a replay. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered, but the description adds nothing beyond them. For a mutation tool it says nothing about permissions, staleness/replay rejection (only in the schema), or what happens to the light state on failure.
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?
One short sentence with no wasted words and the action front-loaded, but its brevity comes from omission rather than discipline — there is simply nothing else to say.
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 setter with no output schema and adequate annotations, the description is still too thin: it omits the staleness/replay contract and any permission or targeting context an agent would need to invoke it correctly.
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?
The description contributes no parameter meaning beyond 'status light' loosely implying the color enum. With 67% schema coverage, the one undocumented parameter (color) is at least bounded by its enum, but the description does not compensate for the gap or explain issued_at/request_id semantics.
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 status light'), which is enough to tell it apart from the reins_* siblings and 'drive'. It is clear but bare: nothing indicates scope, target device, or effect beyond the name.
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?
No when-to-use guidance, no preconditions, and no mention of alternatives. The agent gets no help deciding when this tool is appropriate versus the other five siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.