Get abstract syntax tree for a file. Args: project: Project name path: File path relative to project root max_depth: Maximum depth of the tree (default: 5) include_text: Whether to include node text Returns: AST as a nested dictionary
AI agents call get_ast 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 pure query operation that retrieves and returns the abstract syntax tree structure of a code file. It has no side effects, does not modify any state, and merely provides code analysis data for inspection. The low severity reflects that misuse by an AI agent would only result in unwanted information disclosure, not data loss or external operations.
From the tool's definition Tool name 'get_ast' and description 'Get abstract syntax tree for a file' with return value 'AST as a nested dictionary' indicate data retrieval only. Parameters are all read-only (project name, file path, depth limit, text inclusion flag).
Risk signalsAdmin/system-level operation
Documented attack patterns abuse exactly the kind of access get_ast 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 get_ast:
{
"version": "1",
"default": "deny",
"tools": {
"get_ast": {}
}
}get_ast is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get abstract syntax tree for a file. Args: project: Project name path: File path relative to project root max_depth: Maximum depth of the tree (default: 5) include_text: Whether to include node text Returns: AST as a nested dictionary. 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 get_ast: 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.
get_ast 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 get_ast 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 get_ast. 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.
get_ast 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.