Check if a tree-sitter language parser is available. Args: language: Language to check Returns: Success message
AI agents call check_language_available to retrieve information from Tree Sitter without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a simple informational query that retrieves the status of whether a tree-sitter language parser is available. It does not modify, execute, or delete anything—it only reads and reports state. The blast radius of misuse is minimal; an attacker could only learn what languages are supported, which is low-severity information disclosure. No code is executed or state is altered.
From the tool's definition The tool checks availability of language parsers and returns a success message. It performs a query operation with no modification, creation, or deletion of data. No side effects are described.
Documented attack patterns abuse exactly the kind of access check_language_available gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Tree Sitter, and nothing reaches the server without passing your rules. This is the rule we recommend for check_language_available:
{
"version": "1",
"default": "deny",
"tools": {
"check_language_available": {}
}
}check_language_available is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Check if a tree-sitter language parser is available. Args: language: Language to check Returns: Success message. It is categorised as a Read tool in the Tree Sitter MCP Server, which means it retrieves data without modifying state.
Register the Tree Sitter MCP server in PolicyLayer and add a rule for check_language_available: 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 Tree Sitter. Nothing to install.
check_language_available is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the check_language_available 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 check_language_available. 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.
check_language_available is provided by the Tree Sitter MCP server (wrale/mcp-server-tree-sitter). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 26 Tree Sitter tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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26 Tree Sitter tools catalogued and risk-classified — across an index of 42,500+ MCP servers.