Edit an existing entity. Fields vary by type (same as cantrip_entity_add). Pass well-known fields directly, and any additional fields in the 'fields' object. Extra fields are stored in extensions. Pass project to override .cantrip.json — useful in cloud-hosted or multi-project contexts.
Part of the Cantrip server.
Free to start. No card required.
AI agents use cantrip_entity_edit to create or modify resources in Cantrip. 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 cantrip_entity_edit 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 Cantrip.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"cantrip_entity_edit": {
"limits": [
{
"counter": "cantrip_entity_edit_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Cantrip policy for all 19 tools.
These attack patterns abuse exactly the kind of access cantrip_entity_edit 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.
Edit an existing entity. Fields vary by type (same as cantrip_entity_add). Pass well-known fields directly, and any additional fields in the 'fields' object. Extra fields are stored in extensions. Pass project to override .cantrip.json — useful in cloud-hosted or multi-project contexts.. It is categorised as a Write tool in the Cantrip MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Cantrip MCP server in PolicyLayer and add a rule for cantrip_entity_edit: 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 Cantrip. Nothing to install.
cantrip_entity_edit 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 cantrip_entity_edit 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 cantrip_entity_edit. 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.
cantrip_entity_edit is provided by the Cantrip MCP server (mcp-server-cantrip). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 19 Cantrip tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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