mcp-builder
Pass
Audited by Gen Agent Trust Hub on Oct 28, 2026
Risk Level: SAFEINDIRECT_PROMPT_INJECTIONCOMMAND_EXECUTIONEXTERNAL_DOWNLOADS
Full Analysis
- Indirect Prompt Injection Surface: The evaluation harness in
scripts/evaluation.pyprocesses questions from a user-provided XML file. These questions are then passed to an LLM as part of its instructions, which could allow maliciously crafted input to influence agent behavior. - Ingestion points: The script reads from a file specified by the
eval_fileargument inscripts/evaluation.py(line 347). - Boundary markers: While the system prompt uses XML-like delimiters for the agent's response sections, the untrusted question text is directly included in the message history without separate boundary markers to prevent instruction confusion.
- Capability inventory: The evaluation agent has access to any tools provided by the MCP server being tested, which is connected via
scripts/connections.py. Depending on the server being tested, this could include file or network access. - Sanitization: The script does not perform specific sanitization or escaping on the question text before passing it to the model.
- External Documentation Access: The skill directs the agent to retrieve protocol specifications and SDK details from remote repositories to ensure it has up-to-date information.
- Evidence: References to
modelcontextprotocol.ioandgithub.com/modelcontextprotocolinSKILL.md(lines 53, 67, 72). - Context: These downloads are directed toward official documentation for the technology being utilized and are used to inform the development process.
- Local Process Execution: The evaluation harness includes the ability to launch local server processes to facilitate integration testing.
- Evidence: The
MCPConnectionStdioclass inscripts/connections.py(line 86) and its usage inscripts/evaluation.py(line 369). - Context: This is a standard feature for testing locally developed MCP servers and requires the user to explicitly provide the command and arguments via the command-line interface.
Audit Metadata