Starts RAPID program execution on an ABB controller via RWS. Blocks when errors are detected unless force is enabled to override the safety check.
Start RAPID execution on the controller via RWS. Blocks if errors detected — use force=true to override.
| Name | Required | Description | Default |
|---|---|---|---|
| mode | No | ||
| force | No | Skip safety check and force start even with errors (default: false) |
Changes observed during successful MCP inspections.
v3.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does disclose one valuable behavior: the call blocks on detected errors and force=true overrides that check. It omits other important traits for a mutation tool, such as mastership requirements, what happens if a program is already running, and whether mode=reset changes program-pointer state.
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 action and followed by the key caveat. 'via RWS' is mildly redundant given the tool name, but there is no filler beyond that.
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?
A controller-mutating operation with no annotations, no output schema and one undocumented enum parameter needs more: preconditions, mastership/auth needs, behavior when already running, and what a successful or blocked start returns are all absent.
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 only restates the force parameter, which the schema already documents in full. The mode enum (continue vs reset) is completely undocumented in both schema and description, leaving the highest-impact parameter's semantics unexplained at 50% coverage.
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: 'Start RAPID execution on the controller via RWS.' That clearly distinguishes it from rws_stop_program and rws_reset_pp without needing the schema. It does not explicitly name those siblings, so it stops short of a 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?
Gives one conditional usage rule: use force=true when errors block the start. It does not say when to prefer it over rws_reset_pp or rws_restart_controller, nor whether to check rws_execution_state or rws_check_safety first, which is left to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.