browser_element_screenshot

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

With no annotations, the description carries the burden well: it discloses the scroll-into-view + OffscreenCanvas crop mechanics, that a PNG file is persisted, and that the return value is the saved path. This is meaningful behavioral context. It omits failure modes (e.g., element not found) and any permission/setup expectations, keeping it short of a 5.

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?

Front-loaded with a one-line purpose, then a compact mechanical note, then a tidy Args list. The list format is justified given the 0% schema coverage, though a couple of lines (e.g., the scale explanation) run slightly long.

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?

With no annotations and no output schema, the description covers the return value (saved_to path plus optional data_url) and the operational behavior. It is largely sufficient for correct invocation, missing only error/edge-case behavior and prerequisites.

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 0%, so the description must fully compensate, and it does: every one of the five parameters is documented with semantics and defaults (selector meaning, tab_id default-to-active, default save path, data_url size warning, scale meaning and extension-version requirement). This adds substantial value the bare schema cannot convey.

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 ('Screenshot') and a precisely scoped resource ('a single element'), which implicitly separates it from browser_screenshot and browser_full_page_screenshot. An agent can distinguish the element-level scope 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?

No explicit when-to-use-this-vs-alternative statement; the element-scoping is implied rather than contrasted with the sibling screenshot tools. The only guidance present is parameter-level ('data_url: only if you really need the bytes inline'), which is useful but doesn't tell the agent when to pick this tool over the full-page variants.

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