Get negotiated protocol capabilities (features supported by backend)
AI agents call get_capabilities to retrieve information from React Devtools without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only query to discover what capabilities and features the React DevTools backend supports. It returns informational data about the protocol negotiation and does not create, modify, delete, or execute any operations. The blast radius of misuse is minimal since it only reveals capability information that would already be available through normal debugging operations.
From the tool's definition Tool name 'get_capabilities' and description 'Get negotiated protocol capabilities (features supported by backend)' indicate a query operation that retrieves information about supported features without modifying state or triggering side effects.
Attacks that exploit this kind of access
Get negotiated protocol capabilities (features supported by backend). It is categorised as a Read tool in the React Devtools MCP Server, which means it retrieves data without modifying state.
Register the React Devtools MCP server in PolicyLayer and add a rule for get_capabilities: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches React Devtools. Nothing to install.
get_capabilities is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get_capabilities rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for get_capabilities. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
get_capabilities is provided by the React Devtools MCP server (skylarbarrera/react-devtools-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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