gdb-mcp

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select_frame

Select a stack frame by level (0=innermost) to inspect registers, memory, and locals. Set the active frame for debugging operations.

Instructions

Select a stack frame by level (0 = innermost) for subsequent register/memory/local inspection.

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": {
      "level": "<level>"
    },
    "name": "select_frame"
  }
}

Input Schema

Name	Required	Description	Default
`level`	Yes
`session_id`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 31, 2026

TDQS

A4/5.0

Behavior3/5

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

With no annotations, the description carries the behavioral disclosure burden. It does disclose the stateful nature of the operation: selecting a frame affects subsequent inspections. However, it does not mention error behavior for invalid levels, whether the selection is scoped to a session, or what is returned after selection.

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 with no filler. Every part earns its place: the verb, the target resource, the level semantics, and the follow-on purpose.

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?

For a low-complexity selection tool with no output schema, the description covers the essential call pattern: choose a frame by level, then inspect. It is slightly incomplete in not addressing what happens on invalid levels or how the optional session_id affects behavior, but the core information needed to invoke it correctly is present.

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 input schema provides no descriptions and coverage is 0%, so the description must compensate. It usefully defines the meaning of 'level' with '0 = innermost', but it says nothing about the optional session_id parameter besides what the schema name and default imply. Only one of the two parameters is meaningfully explained.

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 ('Select'), a clear resource ('stack frame'), and a precise selection criterion ('by level'). The clarification that 0 = innermost removes ambiguity and helps distinguish this from related tools like get_backtrace or evaluate.

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 phrase 'for subsequent register/memory/local inspection' clearly communicates when this tool should be used: before inspecting frame-local state. It provides clear context, though it does not explicitly enumerate exclusions or alternatives such as 'use get_backtrace to enumerate frames first.'

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