stmctl-mcp

stm32_write_option_bytes

Change STM32 option bytes (e.g., RDP, nBOOT0) by specifying key-value pairs via SWD. Apply settings like read protection removal directly to the target MCU.

Instructions

Modify target MCU Option Bytes (e.g. set RDP=0xAA to remove read protection, set nBOOT0, etc.).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "option_bytes": "<option_bytes>"
    },
    "name": "stm32_write_option_bytes"
  }
}

Input Schema

Name	Required	Description	Default
`port`	No	Connection port	SWD
`option_bytes`	Yes	Option byte key-value pairs (e.g. 'RDP=0xAA' or 'BOR_LEV=0x00')

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 7, 2026

TDQS

A4.2/5.0

Behavior3/5

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

With no annotations provided, the description must carry the behavioral disclosure burden. It does indicate this is a write operation via 'Modify', and the examples imply changes to security settings. However, it lacks warnings about potential risks (e.g., bricking the MCU, irreversible changes) or prerequisites, leaving the agent with minimal safety context.

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, front-loaded sentence that immediately states the tool's purpose. The examples are concise and informative, with no unnecessary words or repetition.

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

Completeness4/5

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

Given the tool's simplicity (2 parameters, no output schema, straightforward purpose), the description is largely complete. It explains what it does and gives usage examples. However, given the potentially destructive nature of modifying option bytes, a note about caution or side effects would have made it fully complete, but this is not a critical gap.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3. The description adds value by providing concrete example formats for the 'option_bytes' parameter (e.g., 'RDP=0xAA'), which goes beyond the schema's generic 'key-value pairs' text. The 'port' parameter is adequately covered by schema.

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 clearly states the tool modifies target MCU Option Bytes, with a specific verb ('Modify') and resource ('Option Bytes'). It also provides concrete examples (RDP, nBOOT0) that distinguish it from the sibling tool stm32_read_option_bytes.

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 when to use the tool by giving examples like removing read protection, which suggests it's for changing MCU configuration. It doesn't explicitly mention alternatives, but the sibling stm32_read_option_bytes is distinctly for reading, providing context. No exclusions are stated.

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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