WebRun Browser Automation

Create browser session

create_session

Destructive

Create a persistent session in a real Chrome browser running in a WebRun cloud environment (docs.webrun.ai), for multi-step interactive work. Returns a sessionId for subsequent commands. With an initial task the browser may act on third-party websites immediately. Do NOT use this to run or test a saved workflow — use trigger_workflow instead: only a workflow run carries the workflow's own rules, tracking and memory, so a session run will behave differently.

Input Schema

TableJSON Schema

Name	Required	Description
`mode`	No	Session mode (default: default)
`task`	No	Initial task configuration
`model`	No	Optional model name or profile key (from global config). Falls back to the configured default.
`proxy`	No	Proxy configuration. WebRun-managed: { source: "WebRun", country: "GB" }. Custom: { source: "custom", type: "http"\|"socks", host, port, username?, password? }. Omit for no proxy. Social/messaging automation (WhatsApp, Telegram, Instagram, Facebook, X, LinkedIn, TikTok): prefer country = the country the user is in right now — recommend it and confirm the country with them first; a mismatch is the usual cause of refused logins and sessions that log out repeatedly.
`debugC`	No	Enable debug mode on the instance (default: false)
`policyId`	No	Policy ID to apply automation guardrails (domain restrictions, capability controls, LLM role). Optional.
`timezone`	No	IANA timezone name for the session, e.g. "America/New_York", "Europe/London", "Asia/Tokyo". Date/time-sensitive instructions (e.g. "tomorrow morning", "today", "in 2 hours") are interpreted in this timezone. When omitted, follows the WebRun proxy country if one is set (e.g. country "de" → Europe/Berlin); otherwise the browser default.
`environmentId`	No	Environment ID for persistent profile session. Use list_environments to find available IDs. Without this, a disposable instance is used.
`reach_out_mode`	No	Controls proactive chat-platform messages (Telegram/WhatsApp/Slack/Discord/Teams) to bot users on the same environment. Default: "off" — no messages are sent unless this is set explicitly. "guardrail_only" forwards guardrail prompts (CAPTCHA/2FA/verification) to chat when the API caller is offline. "full" also forwards the task result on completion. Each bot user additionally filters by their own reachOutMode preference.

Output Schema

TableJSON Schema

Name	Required	Description
`taskId`	No	Task ID when an initial task was provided
`message`	No
`sessionId`	Yes	Session ID for subsequent commands
`streaming`	No	Endpoints for watching the running browser. Only liveViewURL is a web page — the other two are machine endpoints on a non-standard port.
`environment`	No	Environment this session is bound to, when one was requested

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 7, 2026

changedInput schema / properties / timezone / description

Previous value: -"IANA timezone name for the session, e.g. \"America/New_York\", \"Europe/London\", \"Asia/Tokyo\". Date/time-sensitive instructions (e.g. \"tomorrow morning\", \"today\", \"in 2 hours\") are interpreted in this timezone. Defaults to \"UTC\" when omitted."New value: +"IANA timezone name for the session, e.g. \"America/New_York\", \"Europe/London\", \"Asia/Tokyo\". Date/time-sensitive instructions (e.g. \"tomorrow morning\", \"today\", \"in 2 hours\") are interpreted in this timezone. When omitted, follows the WebRun proxy country if one is set (e.g. country \"de\" → Europe/Berlin); otherwise the browser default."

Changed1 schema field changedSep 6, 2026

changedInput schema / properties / task / properties / files / description

Previous value: -"Optional file IDs to attach (from /files/upload). Max 5 files."New value: +"Optional file IDs to attach: ids returned by POST /files/upload, or any file already in one of the user's environment catalogs (GET /environments/:id/files). Max 5 files."

Changed1 schema field changedSep 2, 2026

changedInput schema / properties / proxy / description

Previous value: -"Proxy configuration. WebRun-managed: { source: \"WebRun\", country: \"GB\" }. Custom: { source: \"custom\", type: \"http\"|\"socks\", host, port, username?, password? }. Omit for no proxy."New value: +"Proxy configuration. WebRun-managed: { source: \"WebRun\", country: \"GB\" }. Custom: { source: \"custom\", type: \"http\"|\"socks\", host, port, username?, password? }. Omit for no proxy. Social/messaging automation (WhatsApp, Telegram, Instagram, Facebook, X, LinkedIn, TikTok): prefer country = the country the user is in right now — recommend it and confirm the country with them first; a mismatch is the usual cause of refused logins and sessions that log out repeatedly."

Changed4 schema fields changedAug 26, 2026

changedOutput schema / properties / streaming / description

Previous value: -"Live-view endpoints for the running browser"New value: +"Endpoints for watching the running browser. Only liveViewURL is a web page — the other two are machine endpoints on a non-standard port."

addedOutput schema / properties / streaming / properties / liveViewURL

Added value: +{
+  "description": "The live-view page. This is the ONLY URL to show a user or open in a browser. Null when the stream is unavailable — say live view is unavailable rather than offering another field.",
+  "type": [
+    "string",
+    "null"
+  ]
+}

addedOutput schema / properties / streaming / properties / webRTCURL / description

Added value: +"WHEP signaling endpoint for a programmatic WebRTC client. POST-only: a browser GET returns HTTP 405. Never show this to a user."

addedOutput schema / properties / streaming / properties / webViewURL / description

Added value: +"Direct MediaMTX player on the streaming host (port 2096), unbranded and often firewall-blocked. Debugging fallback only — prefer liveViewURL."

First observedAug 8, 2026

TDQS

A4.4/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description adds context beyond annotations by warning that with an initial task the browser may act on third-party websites immediately, and by noting the behavioral difference from workflows. It does not cover session lifecycle or authentication, but the openWorld and destructive flags are complemented by this concrete side-effect warning.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loading the core purpose and the critical workflow exclusion. Every sentence earns its place, and there is no fluff or redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a complex tool with 9 parameters and an output schema, the description covers the essential decision points: what it does, what it returns, its side effects, and when not to use it. It does not detail session management (e.g., using terminate_session), but the rich schema and output schema fill in the rest, making this sufficiently complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so all 9 parameters are described in the input schema, including nested objects like proxy and task. The description does not add parameter-level semantics beyond the schema; it only mentions the sessionId return value, which is an output, not a parameter. A baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool creates a persistent Chrome browser session for multi-step interactive work in a WebRun environment, and explicitly contrasts it with trigger_workflow. The verb 'Create' and specific resource 'persistent session' are precise, and the exclusion of workflows distinguishes it from the most likely sibling.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives an explicit when-not-to-use instruction: 'Do NOT use this to run or test a saved workflow' and names the alternative trigger_workflow, explaining why (workflow carries its own rules, tracking, and memory). This is clear, actionable guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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