read_image

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

With no annotations, the description carries the full burden and delivers real behavioral detail: it captures rendered pixels rather than source, asserts no network fetch occurs ('no new request leaves the browser'), and documents the not_found outcome when selector matches nothing. Missing details about re-render timing or how the returned file is scoped keep it from 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 the core action and return value, with the framing sentence about looking at a picture placed second and the no-fetch constraint third. Four short sentences with no filler, though the parenthetical element list and the 'this is how you look' sentence slightly overlap in function.

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?

An output schema exists and the description still clarifies that the return is a file path, plus the not_found failure case. For a two-parameter read-only capture tool the coverage is strong; only the undocumented 'inline' flag leaves a gap an agent might need.

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% and neither parameter is documented in the schema, so the description must compensate. It partially does for selector by explaining the no-match/not_found behavior, but never states that selector is a CSS selector, and the 'inline' parameter is completely unaddressed.

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 (capture) and resource (one element — img, canvas, svg, chart, map) rendered as a PNG file, and the enumerated element types make the scope unambiguous. Combined with 'one element', an agent can distinguish this from the sibling 'screenshot' (full-page capture) without opening either 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?

'This is how you look at a picture on the page' gives clear positive guidance on when to reach for this tool, and 'works for anything drawn, not only img' widens the applicable cases. It does not, however, name the alternative (screenshot) or state when not to use it, so it stops short of the explicit when/when-not/alternative routing of a 5.

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