accessibility_tree

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

With no annotations, the description carries the burden of explaining behavior. It makes the read-only nature clear with 'Get', describes the return structure (hierarchical tree of UI elements with role, title, value, position, size, state), and notes maxDepth controls detail. It does not mention permission requirements or failure behavior, but for a read-only inspection tool this is reasonably transparent.

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?

Three concise sentences, each earning its place: the first states the primary function, the second describes the return data, and the third gives practical depth guidance. It is front-loaded and free of fluff.

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?

There is no output schema, so the description compensates by describing the returned tree's contents and fields. It covers the key calling options adequately for a simple read-only tool, though it omits edge cases like accessibility permission requirements and what happens when no app matches the pid.

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 100%: pid and maxDepth are already well documented in the schema. The description's mention of maxDepth adds little beyond what the parameter description already offers, so the baseline of 3 applies.

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 states a specific verb ('Get') and resource ('accessibility UI element tree of an application'), then enumerates the contents and distinguishes it from screenshot-based approaches. This clearly separates it from the many sibling tools.

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 gives clear usage context: this is the primary way to understand the screen without screenshots, and it advises using maxDepth for detail level. It does not explicitly name alternatives or say when not to use it, so it falls short of a 5.

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