This record as markdown: /tools/io-github-kivanccakmak-yaver/regex-test.md
What regex_test does on Yaver
AI agents invoke regex_test to trigger actions in Yaver. 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.
| Parameter | Type | Required | Description |
|---|---|---|---|
input | string | Yes | Text to match against |
pattern | string | Yes | Regex pattern |
Parameters from the server's own tool schema.
Why regex_test is rated High
The tool runs/executes a regex pattern against text input. While it has no persistent side effects and is essentially read-only in terms of data, it executes computational logic (pattern matching). Severity is low because the blast radius is minimal — it cannot modify data, delete anything, or cause financial harm. It simply evaluates a regex and returns results.
From the tool's definition 'Test a regex pattern against input text' — executes a regex pattern against provided input
Attacks that exploit this kind of access
The rule that runs regex_test safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Yaver, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For regex_test, this is the rule to start with:
regex_test 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Yaver, apply this rule, and every regex_test call is checked against it from then on.
Questions about regex_test
Test a regex pattern against input text. It is categorised as a Execute tool in the Yaver MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
regex_test accepts 2 parameters: input, pattern. Required: input, pattern. The full parameter table on this page comes from the server's own tool schema.
Register the Yaver MCP server in PolicyLayer and add a rule for regex_test: 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 Yaver. Nothing to install.
regex_test 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 regex_test 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 regex_test. 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.
regex_test is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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