browser_state_diff

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

No annotations are provided, so the description must fully disclose behavior. It states the tool shows changes without modifying state, but does not explicitly say it is read-only, or mention permissions or side effects. This is adequate but leaves some ambiguity.

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 very concise: a bold summary, a list of what changes are shown, and a practical use case. 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?

The tool has no output schema, so the description must explain the return. It enumerates the categories of changes (storage, URL, navigations, etc.), which is sufficient for an agent to understand the output. Minor missing detail like the format of timestamps, but overall complete.

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?

The schema already describes each parameter with types and allowed values (anchor, timestamp, 'last_error'), achieving 100% coverage. The description adds context by mentioning 'from browser_timetravel' and giving examples, which adds value beyond the schema.

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: diff two moments and show what changed (localStorage, URL, actions, errors, etc.). It uses a specific verb ('DIFF') and resource ('TWO MOMENTS') and provides a concrete use case, distinguishing it from sibling tools like browser_timetravel or get_state_delta.

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 gives clear context on when to use it ('the fast way to answer what actually changed') and specifies valid inputs (anchor tokens, timestamps, 'last_error'). However, it does not explicitly exclude scenarios or mention alternatives, which would elevate it to a 5.

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