Perform a browser interaction: click, fill, type, check, select, press key, scroll, hover, mousemove, drag, upload, resize, back, forward. Use @eN refs from navigate/snapshot as the target (e.g. '@e2'). CSS selectors also work. drag: requires target (source) and target2 (destination). upload: req...
High parameter count (15 properties)
Part of the Leapfrog MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents use act to create or modify resources in Leapfrog. 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 act repeatedly, creating or modifying resources faster than any human could review. Intercept's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Leapfrog.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
tools:
act:
rules:
- action: allow
rate_limit:
max: 30
window: 60See the full Leapfrog policy for all 37 tools.
Agents calling write-class tools like act have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Write risk category across the catalogue. The same policy patterns (rate-limit, validate) apply to each.
Perform a browser interaction: click, fill, type, check, select, press key, scroll, hover, mousemove, drag, upload, resize, back, forward. Use @eN refs from navigate/snapshot as the target (e.g. '@e2'). CSS selectors also work. drag: requires target (source) and target2 (destination). upload: requires target (file input) and filePaths. resize: requires width and height (no target needed). holdDuration: for click, holds mouse down for N ms (long-press). Returns a fresh snapshot if the page navigated, or just the action result if it didn't.. It is categorised as a Write tool in the Leapfrog MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Add a rule in your Intercept YAML policy under the tools section for act. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Leapfrog MCP server.
act 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 act rule in your Intercept 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 Intercept policy for act. 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.
act is provided by the Leapfrog MCP server (leapfrog-mcp). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Open source. One binary. Zero dependencies.
npx -y @policylayer/intercept