Tool definition integrity in MCP servers
ATR evaluates whether a tool definition can change after approval without integrity controls or renewed approval.
Why it matters
Components can change after approval. Tool definitions and packages may be updated, fetched dynamically, or replaced by lookalike publishers. A previous review may no longer describe the component in use.
In the registry
ATR evaluated this on 21 MCP servers in the 20 published reports, as of Nov. 9th, 2026, and found an issue in 3, across 3 reports.
Each report shows the exact file and lines, why the issue matters, and the recommended fix, with a fix prompt you can paste into your coding agent. Browse the reports.
Questions
What does ATR check for tool definition integrity?
ATR evaluates whether a tool definition can change after approval without integrity controls or renewed approval. Each MCP server is assessed against 26 rules: 14 common, one guardrail, and 11 MCP-specific rules.
Why does tool definition integrity matter?
Components can change after approval. Tool definitions and packages may be updated, fetched dynamically, or replaced by lookalike publishers. A previous review may no longer describe the component in use.
How often does the registry find it?
ATR evaluated this on 21 MCP servers in the 20 published reports, as of Nov. 9th, 2026, and found an issue in 3, across 3 reports.
How do I check my own MCP server?
Request a scan at bluerock.io/scan. Your first scan is free. Each MCP server is assessed against 26 rules: 14 common, one guardrail, and 11 MCP-specific rules.
Source: BlueRock, Component Level Security Analysis for MCP Servers, Agent Skills and Plugins (Oct. 22nd, 2026).