Assert

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

With no annotations provided, the description carries the full burden. It discloses that the tool does not poll and returns pass/fail, which is helpful. However, it does not explain behavior on failure (e.g., throws exception vs returns false), nor does it mention any side effects or conditions for a successful assertion.

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 description is two sentences, front-loaded with the primary action, and contains no irrelevant details. Every sentence adds value: the first defines the action, the second clarifies behavior and points to an alternative.

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?

The description is adequate for a simple assert but lacks important context. With no output schema and many sibling tools, the agent may need to understand element selection semantics and error handling. The description covers the core behavior but leaves gaps in parameter usage and edge cases.

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 14% (only device_id is described). The tool description adds no parameter-specific meaning beyond 'an element', leaving the other six parameters (id, text, index, condition, resource_id, accessibility) unexplained. The description should compensate for the low schema coverage, but it does not.

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's purpose: 'Assert an element is visible or not visible on the current screen.' It uses a specific verb (assert), identifies the resource (element visibility), and distinguishes itself from sibling tools like wait_for (which is for waiting). The return type is also clarified as pass/fail.

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?

The description explicitly contrasts with an alternative: 'without polling (use wait_for to wait)'. This tells the agent when to use this tool (for immediate assertions) and when not to (when waiting is needed). It gives clear usage context relative to a named sibling tool.

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