Notify the language server that a file is open (didOpen).
Risk signalsAccepts file system path (filePath) · Accepts raw HTML/template content (content)
Part of the Java Jdtls server.
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AI agents use java_open_file to create or modify resources in Java Jdtls. 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 java_open_file 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 Java Jdtls.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"java_open_file": {
"limits": [
{
"counter": "java_open_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Java Jdtls policy for all 15 tools.
These attack patterns abuse exactly the kind of access java_open_file 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.
Notify the language server that a file is open (didOpen).. It is categorised as a Write tool in the Java Jdtls MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Java Jdtls MCP server in PolicyLayer and add a rule for java_open_file: 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 Java Jdtls. Nothing to install.
java_open_file 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 java_open_file 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 java_open_file. 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.
java_open_file is provided by the Java Jdtls MCP server (@sachiewonder/java-jdtls-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 15 Java Jdtls tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.