snapshot

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

Annotations already establish read-only and non-destructive behavior, and the description adds important traits: refs remain stable while the page is loaded, iframe refs are encoded as f2e5, diff behavior changes depending on mode, and truncated output is signaled. This is rich behavioral context beyond the structured annotations.

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 dense but front-loaded: purpose and ref format come first, followed by scope, diff semantics, and cutoff advice. It is appropriately sized for a three-parameter tool, though the sentence structure is somewhat run-on.

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?

Given the existing output schema and annotations, the description supplies the remaining operational context an agent needs: how refs work, what scope does, how diff modes behave, and what to do when results are truncated. Nothing essential for correct invocation appears 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 description coverage is 0%, so the description must carry parameter semantics, and it does: scope='#css' limits results, diff=None/True/False are each defined in terms of change-only vs full output, and max_items is tied to cutoff handling. All three parameters are meaningfully explained.

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 a specific verb and resource: listing clickable/typeable elements as ref-tagged labels. It also explains the ref format and iframe ref notation, making the tool's purpose concrete, though it does not explicitly differentiate this listing tool from siblings such as get_text or extract_links.

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?

Usage guidance is mostly implied through the ref selector note and the diff-mode explanation. It explains when to use each diff setting, but does not explicitly say when to call snapshot instead of related sibling tools like find_in_page or get_html.

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