Snapshot the page

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

Annotations already declare readOnlyHint=true, but the description adds substantive behavior: refs may change after navigation (e4→f1e4), and the snapshot text is untrusted website data. The security warning and ref-mutation caveat are genuinely beyond the annotation and valuable to an agent.

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 'Read-only.' followed by tightly-packed, clause-separated facts. Every sentence carries information; density is high but no filler is present.

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 output schema, the description carries the return-value burden and largely meets it: it explains the accessibility snapshot format, the [ref=…] ids, the optional subtree narrowing, and the read-only nature. Truncation behavior is left to the schema, which handles it adequately.

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%, so both ref and maxChars are already documented in the schema. The description's 'Pass ref to get only that element's subtree' mirrors the schema's own text and adds no new syntax or format detail, making baseline 3 appropriate.

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: 'Accessibility snapshot of the current page.' It situates the tool relative to siblings by explaining its output ([ref=…] ids) feeds browser_act, so an agent can distinguish it from browser_open/browser_act without opening a 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?

Clear context is given: use ref ids 'exactly as shown in the latest snapshot,' pass ref to get a subtree, and it 'works during a run.' The linkage to browser_act establishes when to reach for it, though there is no explicit when-not-to-use exclusion.

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