Modify a document in FoundryVTT. IMPORTANT: Before using this tool, you should first retrieve the document using the appropriate get_* tool (e.g., get_actor, get_item) to understand its current structure and field names. Document schemas vary by game system, so inspecting the document first ensur...
AI agents use modify_document to create or update resources in FoundryMCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your FoundryMCP environment.
An AI agent can call modify_document faster than any human can review — one bad instruction and it creates or modifies resources in FoundryMCP by the hundred, each call as confident as the last.
Attacks that exploit this kind of access
Modify a document in FoundryVTT. IMPORTANT: Before using this tool, you should first retrieve the document using the appropriate get_* tool (e.g., get_actor, get_item) to understand its current structure and field names. Document schemas vary by game system, so inspecting the document first ensures you use the correct field paths in your updates. It is categorised as a Write tool in the FoundryMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Foundry MCP server in PolicyLayer and add a rule for modify_document: 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 FoundryMCP. Nothing to install.
modify_document 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 modify_document 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 modify_document. 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.
modify_document is provided by the Foundry MCP server (thestranjer/foundry-vtt-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.