Create a new backend app with isolated database and API endpoints. Returns: app_id, api_url, url (frontend URL), and provisioning status. Example: Input: { name: "my-blog" } Output: { app_id: "app_abc123", api_url: "https://api.butterbase.dev/v1/app_abc123", url: "https://my-blog.butterbase.dev",...
Part of the Mcp server.
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AI agents use init_app to create or modify resources in Mcp. 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 init_app 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 Mcp.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"init_app": {
"limits": [
{
"counter": "init_app_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Mcp policy for all 47 tools.
These attack patterns abuse exactly the kind of access init_app 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.
Create a new backend app with isolated database and API endpoints. Returns: app_id, api_url, url (frontend URL), and provisioning status. Example: Input: { name: "my-blog" } Output: { app_id: "app_abc123", api_url: "https://api.butterbase.dev/v1/app_abc123", url: "https://my-blog.butterbase.dev", _meta: { next_actions: [...] } } URL guide: - api_url: Your API endpoint for database queries, auth, and functions (e.g. https://api.butterbase.dev/v1/app_abc123) - url: Your frontend URL where your deployed site is served (e.g. https://my-blog.butterbase.dev) - These are different! The api_url is for backend requests, the url is where users visit your app. Next steps: Use manage_schema (action: "apply") to define tables, then manage_oauth (action: "configure") for auth. Common errors: - Name already exists: Choose a different name or use manage_app (action: "list") to find existing app - Invalid characters: Use only lowercase letters, numbers, hyphens, underscores - Name too long: Maximum 63 characters The response includes _meta.next_actions with recommended next steps.. It is categorised as a Write tool in the Mcp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MCP server in PolicyLayer and add a rule for init_app: 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 Mcp. Nothing to install.
init_app 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 init_app 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 init_app. 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.
init_app is provided by the MCP server (@butterbase/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 47 Mcp tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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