Browser Accessibility Snapshot

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

With no annotations, the description carries the full burden and does most of it well: it discloses the return format (small indented text list), the stable ref mechanism, and the session-scoped diff behavior including the first-call caveat. It stops short of covering failure modes, permissions, or how mode/sessionId interact in headless vs extension contexts, so it is strong but not exhaustive.

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-loads what the tool returns, then when to prefer it, then the ref-to-selector handoff, then the diff optimization. Each sentence delivers distinct, actionable information with no filler despite the density.

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?

No output schema and no annotations exist, so the description must describe returns and behavior itself, and it does: output shape, ref format, cross-tool selector usage, and diff semantics are all covered. An agent has everything needed to call this correctly.

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 the baseline is 3. The description goes beyond the schema by explaining the cross-tool consequence of refs ('every ref is also a valid CSS selector — pass `[data-mcp-ref="e12"]` directly as the selector argument to browser_click ...'), which meaningfully informs how parameters of this and sibling tools connect.

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 and resource ('Get a compact accessibility-tree view of the page') and enumerates the element kinds returned. It explicitly distinguishes itself from the sibling browser_get_dom by calling itself 'far cheaper ... for finding what to interact with', so an agent can route correctly 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?

Gives explicit when-to-use ('use this first when exploring an unfamiliar page'), names the alternative it supersedes (browser_get_dom), and describes a distinct conditional mode ('Pass diff:true ... for checking the result of a click/type'). This is precisely the routing guidance an agent needs.

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