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

With no annotations, the description carries the full burden. It discloses that the tool waits for load completion, errors on native mobile sessions, and returns only a confirmation rather than page content, even suggesting follow-up tools. This is strong behavioral disclosure, though it omits potential side effects like whether cookies or history are cleared (unlikely but unstated).

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 five sentences, but each delivers critical information: purpose, limitation, return type, sibling differentiation, and alias. It is front-loaded with the core purpose and avoids filler. Slightly dense but well-organized.

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?

For a two-parameter tool with no output schema, the description covers all necessary context: what it does, when it fails, what it returns, how to proceed afterward, how it differs from siblings, and even its historical alias. Nothing essential is missing.

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 coverage is 100% and both parameters have descriptions. The description adds minimal semantic value beyond the schema: it reiterates that sessionId is the addressing mechanism, which is a mild reinforcement. Since the schema already explains the parameters fully, this is a baseline score.

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 action: 'Drive a browser session to a URL and wait for the load to finish.' It specifies the resource (browser session) and the verb, and it explicitly differentiates from siblings by naming web_navigate, ios_safari_navigate, and device_navigate_url, clarifying the distinguishing parameter (sessionId vs pageId vs udid). This leaves no ambiguity about what the tool does.

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 provides explicit when-to-use and when-not-to-use guidance: 'Browser sessions only — a native mobile session has no address bar and this errors there.' It also names the exact alternatives and the criteria for choosing them, making the selection logic transparent.

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