AI agents call get_category to retrieve information from Ynab without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves category details from the YNAB API without modifying, deleting, or executing any operations. The 'Get' verb and query-only semantics place it in the Read category. While it operates in a financial domain (YNAB budget management), it performs no financial transactions, movements of money, or data modifications.
From the tool's definition Tool name 'get_category' and description 'Get details for a single category' indicate a retrieval operation with no side effects.
Attacks that exploit this kind of access
[1 API call] Get details for a single category. It is categorised as a Read tool in the Ynab MCP Server, which means it retrieves data without modifying state.
Register the Ynab MCP server in PolicyLayer and add a rule for get_category: 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 Ynab. Nothing to install.
get_category 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_category 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_category. 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_category is provided by the Ynab MCP server (justmytwospence/ynab-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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