Get item availability for a title/ISBN at a specific branch.
AI agents call availability_at_branch to retrieve information from NLB Singapore Library MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves real-time availability data about library items at specific branches. It has no capability to modify, delete, or create data—it only queries and returns information. The blast radius of misuse is minimal; an agent could query availability repeatedly but cannot cause harm. This is a straightforward Read operation.
From the tool's definition Tool description states 'Get item availability' which is a pure query operation. Sibling tools include 'search_titles' and 'availability_by_title' confirming a read-only search/query pattern. No modifications, deletions, or side effects are performed.
Attacks that exploit this kind of access
Get item availability for a title/ISBN at a specific branch. It is categorised as a Read tool in the NLB Singapore Library MCP Server MCP Server, which means it retrieves data without modifying state.
Register the NLB Singapore Library MCP Server MCP server in PolicyLayer and add a rule for availability_at_branch: 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 NLB Singapore Library MCP Server. Nothing to install.
availability_at_branch 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 availability_at_branch 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 availability_at_branch. 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.
availability_at_branch is provided by the NLB Singapore Library MCP Server MCP server (nikhil-grayscale/nlb-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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