AI agents use set_active_document to create or update resources in PDF Tools — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PDF Tools environment.
This tool performs a state-modifying operation (setting/rehydrating) but does not retrieve data (Read), execute external code (Execute), permanently delete data (Destructive), or handle financial transactions (Financial). The operation is reversible—another document can be set as active. The 'rehydrate' terminology suggests restoring state rather than destructive action.
From the tool's definition Tool name 'set_active_document' and description 'Set or rehydrate the toolkit' indicate the tool modifies the state of the PDF toolkit by selecting or reinitializing the active working document.
Documented attack patterns abuse exactly the kind of access set_active_document gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PDF Tools, and nothing reaches the server without passing your rules. This is the rule we recommend for set_active_document:
{
"version": "1",
"default": "deny",
"tools": {
"set_active_document": {
"limits": [
{
"counter": "set_active_document_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_active_document stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Set or rehydrate the toolkit. It is categorised as a Write tool in the PDF Tools MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the PDF Tools MCP server in PolicyLayer and add a rule for set_active_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 PDF Tools. Nothing to install.
set_active_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 set_active_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 set_active_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.
set_active_document is provided by the PDF Tools MCP server (open-document-alliance/pdf-tools). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 36 PDF Tools tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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36 PDF Tools tools catalogued and risk-classified — across an index of 42,500+ MCP servers.