Nova is a specialized computer-use MCP server with 13 tools for macOS desktop automation (screenshots, mouse/keyboard input, window management, accessibility tree reading). Tool definitions are well-structured with consistent schemas and descriptions, but several tools lack sufficient documentation of their side effects, idempotency guarantees, and recovery paths. Naming is verb-forward and mostly clear, though some tools expose low-level coordinate-based APIs that require agent reasoning about screen layout. Parameter types are properly specified (enums for choices, numbers for coordinates), but descriptions for several tools could better explain WHEN to use them and what makes them distinct from alternatives. Error handling is minimal, most tools lack guidance on failure recovery or actionable next steps. The server implements tool annotations (destructiveHint) for some tools, which is a small positive, but not comprehensively.

• Consolidate read_ui and ax_read into a single tool with a clear name like 'read_accessibility_tree'. If they must differ, document the semantic distinction in both descriptions.
• Rename jargon-heavy tools: ax_read → read_accessibility_tree, ax_activate → activate_ui_element, chrome_semantic → interact_with_chrome (or split into multiple focused tools).
• Add output schemas for all tools. At minimum, document what fields each tool returns. Example: 'Returns {success: boolean, error?: string, coordinates?: {x, y}}' or 'Returns {text: string, marks: [{id: number, label: string, role: string}]}'.
• Add recovery guidance to every tool that modifies state. Example: 'On failure: If coordinates are invalid, call screenshot() to refresh the coordinate frame. If click fails, verify the UI element is visible and in the foreground.'
• Clarify coordinate frames. Explicitly state: 'All x/y coordinates are relative to the most recent screenshot, with origin at top-left (0,0). If the display resolution changed, re-run screenshot() to get a new coordinate frame.'
• Document idempotency for each tool. Example: 'type() is idempotent only if the target text field is initially empty. On retry, text may accumulate. Recommend calling screenshot() between retries to verify state.'
• For ax_read, document the mark assignment algorithm and output structure. Example: 'Returns an accessibility tree as JSON {type, role, label, children: [{...}]}. Each interactive element is assigned a mark ID (integer) visible in the JSON, which can be passed to ax_activate or click_mark.'

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry