Processes and transforms YAML, JSON, XML, TOML, and properties files using yq expressions. Accepts input from a file path or inline string. Returns the transformed result.
AI agents invoke yq to trigger actions in Http. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
yq supports arbitrary expression evaluation including file reads, writes, and complex transformations. The tool accepts user-supplied yq expressions which can read from and write to the filesystem, making this an Execute-level risk.
From the tool's definition 'Processes and transforms YAML, JSON, XML, TOML, and properties files using yq expressions' — executes arbitrary yq expressions against files or inline strings
Documented attack patterns abuse exactly the kind of access yq gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Http, and nothing reaches the server without passing your rules. This is the rule we recommend for yq:
{
"version": "1",
"default": "deny",
"tools": {
"yq": {
"limits": [
{
"counter": "yq_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}yq stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Processes and transforms YAML, JSON, XML, TOML, and properties files using yq expressions. Accepts input from a file path or inline string. Returns the transformed result. It is categorised as a Execute tool in the Http MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Http MCP server in PolicyLayer and add a rule for yq: 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 Http. Nothing to install.
yq is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the yq 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 yq. 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.
yq is provided by the Http MCP server (@paretools/http). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Http, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
202 Http tools catalogued and risk-classified — across an index of 43,000+ MCP servers.