Call a z/OS Connect REST API to interact with mainframe programs. Maps JSON to COBOL copybooks automatically.
Risk signalsAccepts raw HTML/template content (payload)
Part of the Ibmz server.
Free to start. No card required.
AI agents use zos_connect_call_service to create or modify resources in Ibmz. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call zos_connect_call_service repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Ibmz.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"zos_connect_call_service": {
"limits": [
{
"counter": "zos_connect_call_service_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Ibmz policy for all 13 tools.
These attack patterns abuse exactly the kind of access zos_connect_call_service gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Call a z/OS Connect REST API to interact with mainframe programs. Maps JSON to COBOL copybooks automatically.. It is categorised as a Write tool in the Ibmz MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Ibmz MCP server in PolicyLayer and add a rule for zos_connect_call_service: 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 Ibmz. Nothing to install.
zos_connect_call_service is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the zos_connect_call_service 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 zos_connect_call_service. 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.
zos_connect_call_service is provided by the Ibmz MCP server (ibmz-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 13 Ibmz tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.