app_snapshot

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

Despite no annotations, the description fully discloses the read-only nature and the expected output: page title, visible body text, and interactive elements with role, text/aria-label, and CSS selector. It also warns about the brittleness of the selectors, adding value beyond the schema.

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?

Two sentences that are front-loaded with the core purpose, efficiently describe the output, and include practical usage advice. Every sentence adds value without redundancy.

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?

Given the tool has zero parameters and no output schema, the description covers all necessary information: what is returned (title, text, interactive elements), the format (role, text/aria-label, CSS selector), and actionable usage tips. It is complete for an agent to understand and use the tool correctly.

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?

No parameters exist (schema coverage 100%), so the description does not need to provide parameter details. Baseline score of 4 applies as there is no additional context needed.

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 clearly states the tool reads the current app window state and lists the specific data returned (page title, body text, interactive elements with attributes). It distinguishes itself from sibling tools like app_screenshot by recommending use over screenshots.

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?

Explicitly advises when to use this tool ('Use this instead of a screenshot when you just need to know what's on screen and actionable') and provides guidance on how to use the output (prefer targeting by element text over the provided brittle selectors in other tools).

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