stm32-stlink-mcp

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Read core registers

register_read

Read core register values (PC, SP, R0, etc.) from a connected STM32 target via GDB MI to inspect CPU state during debugging sessions.

Instructions

Reads named core registers (default: all general-purpose + sp/lr/pc/xpsr) via gdb MI.

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": {
      "sessionId": "<sessionId>"
    },
    "name": "register_read"
  }
}

Input Schema

Name	Required	Description	Default
`registers`	No	Register names, e.g. ['pc','sp','r0']. Default: all core registers.
`sessionId`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 21, 2026

TDQS

A3.8/5.0

Behavior3/5

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

With no annotations, the description must convey behavior. It states 'reads', indicating a read-only operation, but provides no details on error conditions, side effects, or prerequisites like an active debug session. The mention of 'via gdb MI' adds implementation context but not behavioral transparency.

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, concise sentence that includes the essential purpose, the optional parameter behavior, and the implementation method. No redundant or unnecessary information.

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?

The description is adequate for a simple read operation, giving the default register set and the mechanism. While it doesn't explain the return format or the necessity of sessionId, that is partially covered by the schema and the overall simplicity of the tool. It could benefit from a note on active session requirements, but is largely complete.

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?

The description adds value for the 'registers' parameter by explaining the default, and the schema also provides a description for it. However, the 'sessionId' parameter is required but not explained in either the description or the schema, leaving a gap in parameter semantics.

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?

Clearly states it reads core registers, specifying the verb 'reads' and the resource 'core registers'. It also distinguishes from sibling tools like read_fault_registers by specifying 'core' and the default register set.

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

Usage Guidelines3/5

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

Implicitly suggests usage for reading general-purpose registers, but does not explicitly compare with alternatives like read_fault_registers or evaluate_expression. No direct when-to-use guidance beyond the default set.

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