Use the native accessibility tree to read, click, and type in web apps—including canvas-based SPAs—enabling reliable UI automation without screenshots.
Native accessibility tree via chrome.debugger (CDP Accessibility domain) — for canvas SPAs (Telegram web, Trad…
| Name | Required | Description | Default |
|---|---|---|---|
| name | No | ||
| role | No | ||
| text | No | ||
| match | No | click/type: node matcher | |
| tabId | Yes | ||
| action | Yes | ||
| nameContains | No | read: substring AX name match |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description carries the entire burden. It discloses the CDP mechanism but not behavioral implications of the action enum (especially click/type side effects), permission requirements, or limitations of the debugger-based approach.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The opening is concise and front-loaded with mechanism and purpose, but the description appears truncated ('Trad…') and omits structured details about actions and matching, making it no more than adequately compact.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
A 7-parameter tool with an action enum, nested match object, no output schema, and no annotations needs substantially more context. The agent learns what the tool is for but not how to invoke it correctly or interpret results.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is only 29%, yet the description adds no parameter-level meaning for action, tabId, match, or text. It only contextualizes the resource, leaving the agent to infer how to construct a valid call.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description names a specific resource ('native accessibility tree') and mechanism ('chrome.debugger (CDP Accessibility domain)') with a clear use case ('canvas SPAs'). It lacks an explicit verb like 'read' or 'get', and it does not explicitly distinguish among the action variants, so it falls short of a 5.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It clearly scopes use to canvas-based SPAs such as Telegram web, which signals when DOM-oriented sibling tools may be ineffective. It does not mention exclusions or alternative tools, so it misses full routing guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.