regex_tester
Regex Tester (timeout-guarded) — Test a regex pattern against text (findall/search/fullmatch/split/sub) using a timeout-guarded engine so a catastrophic pattern fails fast instead of hanging.
This record as markdown: /tools/com-wingmanprotocol-agent-gateway/regex-tester.md
What regex_tester does on Gateway
AI agents invoke regex_tester to trigger actions in Gateway. 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 |
|---|---|---|---|
mode | string | — | findall | search | fullmatch | split | sub (default findall) |
text | string | Yes | Text to match against |
flags | array | — | List of flag letters: i, m, s, x |
pattern | string | Yes | Regex pattern to test |
timeout_ms | number | — | Timeout guard in milliseconds, 0-2000 (default 200) |
replacement | string | — | Replacement text (mode=sub only) |
Parameters from the server's own tool schema.
Why regex_tester is rated High
This tool executes regex operations against arbitrary input text. The mention of 'catastrophic pattern' and the need for a timeout guard indicates the tool runs potentially complex computational operations. While it doesn't modify data, it executes code-like pattern matching that could be resource-intensive. The timeout guard mitigates worst-case scenarios, keeping severity at medium rather than high.
From the tool's definition 'Test a regex pattern against text (findall/search/fullmatch/split/sub) using a timeout-guarded engine so a catastrophic pattern fails fast instead of hanging'
Attacks that exploit this kind of access
The rule that runs regex_tester safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Gateway, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For regex_tester, this is the rule to start with:
regex_tester 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 Gateway, apply this rule, and every regex_tester call is checked against it from then on.
Questions about regex_tester
Regex Tester (timeout-guarded) — Test a regex pattern against text (findall/search/fullmatch/split/sub) using a timeout-guarded engine so a catastrophic pattern fails fast instead of hanging. It is categorised as a Execute tool in the Gateway MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
regex_tester accepts 6 parameters: mode, text, flags, pattern, timeout_ms, replacement. Required: text, pattern. The full parameter table on this page comes from the server's own tool schema.
Register the Gateway MCP server in PolicyLayer and add a rule for regex_tester: 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 Gateway. Nothing to install.
regex_tester 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_tester 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_tester. 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_tester is provided by the Gateway MCP server (https://wingmanprotocol.com/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
More on Gateway, and thousands of servers like it.
Across the catalogue