stmctl-mcp

stm32_start_swv_trace

Connect to STM32 Serial Wire Viewer (SWO/ITM) and stream printf log outputs, with configurable ITM port and clock frequency.

Instructions

Connect to Serial Wire Viewer (SWO/ITM) and stream printf log outputs.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "stm32_start_swv_trace"
  }
}

Input Schema

Name	Required	Description	Default
`log_file`	No	Optional log file path to record SWO output
`port_number`	No	ITM port number (0-31 or 'all')	0
`clock_freq_mhz`	No	MCU System Clock frequency in MHz (e.g. 16, 84, 168, 480)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 7, 2026

TDQS

A3.9/5.0

Behavior3/5

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

With no annotations, the description carries the full burden of behavioral disclosure. It states the action ('Connect and stream'), but it does not reveal important behavioral traits such as whether the operation blocks, how to terminate the stream, or that it may alter target trace settings. This is a moderate gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single sentence that delivers the essential purpose and action without unnecessary words. It is front-loaded and every word contributes to understanding.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the core purpose and the schema documents parameters, but it lacks context about the streaming behavior (e.g., ongoing capture, stopping method) and does not describe return values or output format. Since there is no output schema, this is a noticeable gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the schema already documents all three parameters. The description adds no additional meaning beyond the schema, such as usage examples or relationships between parameters. This hits the baseline for high schema coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Connect') and resource ('Serial Wire Viewer (SWO/ITM)') and clearly states the action ('stream printf log outputs'). This distinguishes it from sibling tools like stm32_connect_info, which focuses on connection details, and stm32_raw_cli, which is a general CLI. The purpose is unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies the tool is used when you need to view printf logs over SWO/ITM, providing clear context. However, it does not explicitly mention when not to use it or name alternative tools, so it stops short of a full when/when-not/alternatives explanation.

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

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