This record as markdown: /tools/io-github-kivanccakmak-yaver/acl-call-peer-tool.md
What acl_call_peer_tool does on Yaver
AI agents invoke acl_call_peer_tool to trigger actions in Yaver. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
| Parameter | Type | Required | Description |
|---|---|---|---|
peer_id | string | Yes | Peer ID |
arguments | object | — | Tool arguments |
tool_name | string | Yes | Tool name |
Parameters from the server's own tool schema.
Why acl_call_peer_tool is rated High
This tool acts as a proxy executor, capable of invoking any tool on a connected MCP peer. The actual effect depends on which tool is called remotely, but since it can execute arbitrary tools (including destructive or financial ones) on peer systems, it represents a high blast radius. The most severe applicable category is Execute, as it triggers external operations whose effects depend on arguments.
From the tool's definition 'Call a tool on a connected MCP peer' — this tool executes arbitrary tools on remote/peer systems
Attacks that exploit this kind of access
The rule that runs acl_call_peer_tool safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Yaver, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For acl_call_peer_tool, this is the rule to start with:
acl_call_peer_tool stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Yaver, apply this rule, and every acl_call_peer_tool call is checked against it from then on.
Questions about acl_call_peer_tool
Call a tool on a connected MCP peer. It is categorised as a Execute tool in the Yaver MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
acl_call_peer_tool accepts 3 parameters: peer_id, arguments, tool_name. Required: peer_id, tool_name. The full parameter table on this page comes from the server's own tool schema.
Register the Yaver MCP server in PolicyLayer and add a rule for acl_call_peer_tool: 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 Yaver. Nothing to install.
acl_call_peer_tool is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the acl_call_peer_tool 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 acl_call_peer_tool. 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.
acl_call_peer_tool is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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