List environment variable keys from .env files with inferred value types/formats. Never exposes actual values — only keys, types (string/number/boolean/empty), and formats (url/email/ip/path/uuid/json/base64/csv/dsn/etc). Read-only, no side effects, safe for secrets. Use to understand project con...
AI agents call get_env_vars to retrieve information from Trace without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves metadata about environment variables (keys, inferred types, and formats) without exposing sensitive values. It performs pure data retrieval with no ability to modify, delete, or execute operations. The explicit statement 'Read-only, no side effects' and 'safe for secrets' confirms it is strictly informational and poses minimal risk.
From the tool's definition Tool description states 'List environment variable keys' and 'Never exposes actual values — only keys, types, and formats' and explicitly marked 'Read-only, no side effects, safe for secrets'
Documented attack patterns abuse exactly the kind of access get_env_vars gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Trace, and nothing reaches the server without passing your rules. This is the rule we recommend for get_env_vars:
{
"version": "1",
"default": "deny",
"tools": {
"get_env_vars": {}
}
}get_env_vars is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List environment variable keys from .env files with inferred value types/formats. Never exposes actual values — only keys, types (string/number/boolean/empty), and formats (url/email/ip/path/uuid/json/base64/csv/dsn/etc). Read-only, no side effects, safe for secrets. Use to understand project configuration without accessing actual values. Pass. It is categorised as a Read tool in the Trace MCP Server, which means it retrieves data without modifying state.
Register the Trace MCP server in PolicyLayer and add a rule for get_env_vars: 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 Trace. Nothing to install.
get_env_vars 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_env_vars 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_env_vars. 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_env_vars is provided by the Trace MCP server (nikolai-vysotskyi/trace-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 178 Trace tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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178 Trace tools catalogued and risk-classified — across an index of 42,500+ MCP servers.