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wait_until

Polls for observable UI conditions (window, element, focus, terminal, URL) to replace screenshot-polling loops. Returns success or timeout with actionable suggestions.

Instructions

Purpose: Server-side poll for an observable condition — eliminates screenshot-polling loops when waiting for state changes. Details: condition selects what to watch: window_appears/window_disappears (target.windowTitle required), focus_changes (optional target.fromHwnd), element_appears/value_changes (target.windowTitle + target.elementName required, UIA; min 500ms interval), ready_state (target.windowTitle; visible + not minimized), terminal_output_contains (target.windowTitle + target.pattern required [+target.regex:true], needs terminal tools loaded), element_matches (target.by + target.pattern required, needs browser tools loaded), url_matches (target.pattern required [+target.regex:true]; matches the active tab's location.href via CDP — use for SPA route changes, redirects, OAuth flows). Returns {ok:true, elapsedMs, observed} on success, or WaitTimeout error with suggest hints. timeoutMs default 5000 (max 60000). Prefer: Use instead of run_macro({sleep:N}) + screenshot loops. Use terminal_output_contains to detect CLI command completion. Use element_matches for browser DOM readiness after navigation. Use url_matches when the URL is the most reliable signal (SPA routing / redirect cascades). Caveats: terminal_output_contains, element_matches, and url_matches require a browser CDP connection (open --remote-debugging-port=9222 first). element_appears/value_changes spawn a UIA process per poll — interval clamped to 500ms minimum. On elapsed-timeout the response is {ok:false, code:'WaitTimeout', error, suggest:[...]}; the suggest[] array lists three fixed actions: 'Increase timeoutMs', 'Verify the target is correct', 'Inspect intermediate state with screenshot(detail='meta')'. Non-timeout failures also occur — pre-poll validation and missing-hook errors classify as code:'ToolError' (read the descriptive error message), and CDP probe errors (url_matches / element_matches conditions) surface as code:'BrowserNotConnected' (re-attach via browser_open). Branch on code rather than assume WaitTimeout. Examples: wait_until({condition:'window_appears', target:{windowTitle:'Save As'}, timeoutMs:10000}) wait_until({condition:'terminal_output_contains', target:{windowTitle:'Terminal', pattern:'$ '}, timeoutMs:30000}) wait_until({condition:'element_matches', target:{by:'text', pattern:'Submit', scope:'#checkout-form'}}) wait_until({condition:'url_matches', target:{pattern:'/dashboard'}, timeoutMs:15000}) wait_until({condition:'url_matches', target:{pattern:'^https://app\\.example\\.com/orders/[0-9]+$', regex:true}})

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
targetNoTarget descriptor — fields used depend on condition. Accepts an object literal or a JSON-stringified object.
includeNoOptional response-shape opt-in. `['envelope']` returns the self-documenting envelope (`_version` / `data` / `as_of` / `confidence`). `['raw']` forces raw shape (overrides DESKTOP_TOUCH_ENVELOPE=1 server default). Default behaviour is raw shape (compat with existing clients).
conditionYesCondition to wait for. See per-condition target requirements.
timeoutMsNoMaximum time to wait (default 5000ms)
intervalMsNoPoll interval (default 200ms — terminal_output_contains uses 500 internally)
Behavior5/5

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

Without annotations, the description fully discloses behavior: polling mechanics, return format ({ok:true, elapsedMs, observed}), timeout behavior (WaitTimeout with suggest hints), non-timeout failure modes (ToolError, BrowserNotConnected), and implementation details (UIA process per poll, interval clamping).

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

Conciseness4/5

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

The description is well-structured with clear sections (Purpose, Details, Prefer, Caveats, Examples) and front-loaded purpose. While verbose, each sentence adds unique value; minor redundancy in some examples could be trimmed.

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

Completeness5/5

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

Given the tool's complexity (9 conditions, multiple error paths, prerequisites), the description is exhaustive: it covers all conditions, target requirements, error codes, and provides examples for various use cases. The lack of an output schema is compensated by clear return value documentation.

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

Parameters5/5

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

With 100% schema coverage, the description adds significant value by explaining each condition's target requirements, providing examples, and elaborating on optional parameters like intervalMs and include, making the tool far more usable than the schema alone.

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's purpose as a server-side poll for observable conditions, listing specific conditions (e.g., window_appears, url_matches) and distinguishing it from screenshot-polling loops by sibling tools like run_macro and screenshot.

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?

Explicitly advises when to use this tool over alternatives (e.g., 'Use instead of run_macro({sleep:N}) + screenshot loops'), provides condition-specific guidance (use url_matches for SPA route changes), and includes caveats about prerequisites (browser CDP connection) and error handling with suggested actions.

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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