frame

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

With no annotations, the description carries the full burden and does disclose the key non-obvious trait: the switch is stateful and persists until changed or a new page load. That is exactly the kind of side effect an agent must know. It does not cover failure behavior (e.g., frame not found, timeout handling beyond the schema's timeoutMs) or return values, so it falls short of full transparency.

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?

Four sentences, front-loaded with the purpose and impact on other tools, then the action semantics, then the lifetime rule. No filler; every sentence contributes actionable information.

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 stateful 5-parameter tool with a nested selector object, no annotations, and no output schema, the description covers purpose, per-action semantics, and the state lifetime plus how to revert. It omits error/timeout behavior and any indication of what a successful call returns, which keeps it just short of fully complete.

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%, and the schema already documents action, index, nameOrId, selector, and timeoutMs with the precedence rules ('used when no selector is given'). The description restates the action meanings and the selector/index/nameOrId alternatives but adds no format, precedence, or fallback detail beyond what the schema provides, so baseline 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?

States a specific verb+resource ('Move into or out of an iframe') and immediately scopes it against siblings by noting elements inside a frame cannot be found by other tools until you switch in. An agent can distinguish this from window, click, or find_element without opening any schema.

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?

Gives an explicit trigger (elements inside embedded widgets, rich-text editors, payment fields are invisible to other tools) and a clear cleanup rule ('switch back with default when you are done inside the frame'). Each action value is defined inline, so the when-to-use and how-to-exit guidance is complete.

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