selenium_start
Start a first-class Selenium/WebDriver Chrome session on this runtime host. Use for daily browser tasks that should explicitly go through WebDriver instead of CDP. Does not bypass CAPTCHA or site auth; hand off to the user when needed.
This record as markdown: /tools/io-github-kivanccakmak-yaver/selenium-start.md
What selenium_start does on Yaver
AI agents invoke selenium_start 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 |
|---|---|---|---|
url | string | — | Optional initial URL |
width | integer | — | Viewport width, default 1280 |
height | integer | — | Viewport height, default 800 |
headful | boolean | — | Show Chrome window visibly |
profile | string | — | Persistent Chrome profile name or absolute user-data-dir |
session_id | string | — | Optional custom session ID |
Parameters from the server's own tool schema.
Why selenium_start is rated High
Selenium/WebDriver sessions are execute-category tools because they automate external browser operations and trigger real-world side effects (page navigation, interactions, data submission).
From the tool's definition Tool description states it 'Start[s] a first-class Selenium/WebDriver Chrome session' and is used for 'browser tasks that should explicitly go through WebDriver.' These are external operations that execute browser automation whose effects depend on how the…
Risk signalsAccepts URL/endpoint input (url)
Attacks that exploit this kind of access
The rule that runs selenium_start 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 selenium_start, this is the rule to start with:
selenium_start 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 selenium_start call is checked against it from then on.
Questions about selenium_start
Start a first-class Selenium/WebDriver Chrome session on this runtime host. Use for daily browser tasks that should explicitly go through WebDriver instead of CDP. Does not bypass CAPTCHA or site auth; hand off to the user when needed. 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.
selenium_start accepts 6 parameters: url, width, height, headful, profile, session_id. 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 selenium_start: 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.
selenium_start 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 selenium_start 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 selenium_start. 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.
selenium_start 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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