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

With no annotations, the description carries the full behavioral burden. It usefully discloses statefulness and a pay-per-call cost model ($0.005 USD / x402), which an agent must know before invoking. However, it omits failure behavior (what happens on a first check with no stored snapshot), snapshot retention, and whether payment failure aborts the call.

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?

Two short sentences, front-loaded with the core operation and then the cost model. No filler, no repetition of the tool name.

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?

For a two-parameter tool with no output schema and no annotations, the description covers the core mechanic and cost but leaves the stateful workflow (store before check), return shape, and first-run behavior unexplained. Adequate but with clear gaps an agent would hit in practice.

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 url and the check/store enum are already documented in the schema; the baseline is 3. The description adds only the vague notion of 'past snapshots', which loosely maps to the store action, but supplies no extra syntax, defaults, or ordering semantics.

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 ('DOM snapshotting and diff detection', 'compares page content against past snapshots'), which is far more informative than the name alone. It doesn't explicitly contrast itself with siblings like run_spider_view_scan or extract_website_metadata, but the change-detection purpose is unambiguous.

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?

There is no statement of when to use this versus the many sibling checks, nor of the prerequisite workflow (that a snapshot must be stored before a check is meaningful). The 'stateful' wording hints at a store-then-check sequence but never spells it out.

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