Use this when a user asks how much an NSE stock, index, or option changed over yesterday or from the previous close. PROD is recommended for market data access.
AI agents call get_yesterday_change to retrieve information from Nubra MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries historical price change data with no side effects. It performs a simple lookup of previous close price movements—a classic Read operation. The low severity reflects that misuse by an AI agent (e.g., querying unintended symbols) poses no financial risk, operational risk, or data integrity threat. No authentication, authentication state changes, orders, or deletions occur.
From the tool's definition Tool description explicitly states it retrieves how much a stock/index/option 'changed' (past tense, historical data) and recommends PROD for 'market data access', which is a read-only operation.
Attacks that exploit this kind of access
Use this when a user asks how much an NSE stock, index, or option changed over yesterday or from the previous close. PROD is recommended for market data access. It is categorised as a Read tool in the Nubra MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Nubra MCP Server MCP server in PolicyLayer and add a rule for get_yesterday_change: 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 Nubra MCP Server. Nothing to install.
get_yesterday_change 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_yesterday_change 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_yesterday_change. 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_yesterday_change is provided by the Nubra MCP Server MCP server (socials-zanskar/nubra-mcp-server). 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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