Reconstruct DOM at a time

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

Annotations declare readOnlyHint=true, which the description does not contradict. The description adds behavioral traits beyond annotations: it applies mutations on top of the nearest full snapshot, returns JSON with specific fields (baseSnapshotTs, mutationsApplied, html), clips HTML to 24000 chars, and fails if no full snapshot exists. This provides useful context for agent decision-making.

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 two sentences, front-loaded with the main action, and includes essential details: timestamp usage, mutation application, return format, clipping limit, and failure condition. Every sentence adds value with no wasted words.

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 tool has 3 parameters, no output schema, and annotations provide readOnly hint, the description adequately covers the return structure and limits. It could mention behavior for invalid selectors, but overall it is complete enough for typical use cases.

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 coverage is 100% for all three parameters. The description adds meaning: for ts, it specifies 'Epoch-ms timestamp' and suggests sources (get_session_summary, error rows, get_user_action_before_error). For selector, it clarifies behavior ('return only that subtree. Omit to return the full document'). This adds value beyond the schema descriptions.

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 the tool's purpose: 'Reconstruct the page DOM as it existed at a timestamp (or a selector subtree within it) and return it as HTML.' This is a specific verb (reconstruct) and resource (DOM at a timestamp), and it distinguishes from siblings like get_session_summary (metadata) or query_dom_history (likely different).

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?

The description provides clear context: it uses timestamps from get_session_summary, error rows, or get_user_action_before_error, and mentions failure condition if no full snapshot exists. However, it does not explicitly state when not to use this tool or suggest alternatives, though the context is sufficient for most cases.

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