set_emotionDisplays a chosen emotion on the robot’s OLED face and an optional message, temporarily overriding sensor-driven expressions for about five seconds.
Show an expression on the robot's face display (emulated SSD1306 128×64 OLED); the message appears in the top text line and scrolls if long. Held ~5 s before sensor-driven emotions resume.
| Name | Required | Description | Default |
|---|---|---|---|
| emotion | Yes | ||
| message | No | Speech text shown under the face |
Changes observed during successful MCP inspections.
v1.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full burden and does a fair job: it discloses the display technology and dimensions, the text placement and overflow/scroll behavior, and critically the ~5 s hold before sensor-driven emotions resume. Gaps remain on what happens to a long message vs. the face, and whether the state can be cleared early.
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 tight sentences with no waste; the primary action leads, followed by rendering detail and then the temporal/state behavior that matters most for correct invocation.
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 2-parameter, no-annotation, no-output-schema tool, the description covers action, rendering, duration, and state restoration — enough to call it correctly. The message-placement inconsistency with the schema is the one thing an agent could still get wrong.
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 50% — the enum for 'emotion' is self-documenting and 'message' already has a schema description. The description adds rendering behavior for the message (top text line, scrolls if long), but this conflicts with the schema's 'Speech text shown under the face', leaving the agent unsure where the text actually renders.
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?
Specific verb and resource: 'Show an expression on the robot's face display', with the underlying hardware named (emulated SSD1306 128x64 OLED). It does not, however, distinguish itself from overlapping siblings such as set_display, display_text, or draw_display, which an agent could reasonably confuse it with.
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?
Usage is only implied: 'Held ~5 s before sensor-driven emotions resume' suggests this is a transient manual override of automatic emotion behavior. There is no explicit statement of when to choose this over display_text or set_display, nor any exclusion.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.