gdb-mcp

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write_memory

Write raw bytes, specified as a hex string, to a target process's memory at a given address, enabling direct memory patching during debugging for security research and exploit development.

Instructions

Write raw bytes (given as a hex string, e.g. '9090c3' or '90 90 c3') to the inferior's memory.

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": {
      "address": "<address>",
      "hex": "<hex>"
    },
    "name": "write_memory"
  }
}

Input Schema

Name	Required	Description	Default
`hex`	Yes
`address`	Yes
`session_id`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 31, 2026

TDQS

B3.1/5.0

Behavior2/5

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

Annotations are absent, so the description alone must disclose behavior. It reveals the write side effect only by saying 'Write raw bytes,' and gives no warning about memory corruption, alignment, permissions, or whether the target must be stopped. It does add the hex-format detail, but the behavioral risks of a memory write are left unstated.

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?

A single sentence with an inline example; no redundant words or restating of the name. The crucial formatting constraint is front-loaded. It is appropriately concise for a simple write operation.

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

Completeness2/5

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

With no annotations and no output schema, the description should cover prerequisites, side effects, and parameter semantics, but it only covers hex formatting. An agent has no way to know what session_id selects, what the response is, or whether the inferior must be stopped. This is minimal and incomplete for a mutating tool.

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

Parameters2/5

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

The description explains the format of hex with two concrete examples, which is useful. However, it says nothing about address representation (string vs integer, base) or the meaning and role of session_id, leaving two of three parameters underdocumented. With 0% schema coverage, this is a significant gap.

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?

States a specific action ('Write raw bytes') and a specific target ('the inferior's memory'), with a concrete hex example. The name and description clearly distinguish it from read_memory and write_register. It is unambiguous about what resource it operates on.

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

Usage Guidelines2/5

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

No guidance on when to choose this tool over read_memory, set_breakpoint, or execute_command. It does not mention prerequisites (e.g., a running or stopped inferior) or when an alternative would be more appropriate. The intended use is only implied by the name and verb.

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