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

Annotations already declare the read-only, non-destructive, idempotent, closed-world profile, yet the description adds genuinely new behavioral facts: no API key needed, a hard 32768-byte total JSON input cap, an output budget, and an explicit guarantee of no network fetch or automatic paid fallback. These cost/limit/no-side-effect disclosures go beyond the annotations and help an agent predict behavior.

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 the key operational fact ('FREE, no key') and packs constraints into short clauses with no filler sentences. It is dense and efficient, though the somewhat vague 'Explicit shared output budget and scope' phrase is less informative than its length suggests.

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?

Return values need not be described since an output schema exists, and the description covers cost, input size, and no-fetch guarantees. But it omits parameter semantics for maxChars/sourceUrl and offers no routing guidance among the numerous delta/compare siblings, so it is only minimally complete for a 4-parameter tool in a crowded namespace.

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 0%, so the description must carry the parameter burden, but it only clarifies beforeHtml/afterHtml (via 'before/after HTML') and gesturally points at an 'output budget' that may map to maxChars. It never explains maxChars truncation semantics or what sourceUrl is used for, leaving two of four parameters undocumented.

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 (return) and resource (added and removed content blocks) plus the required input (before/after HTML), so the core function is unmistakable. It implicitly separates itself from fetch-based siblings via 'Supplied data only; no fetch,' but never names web_page_delta or the other delta/compare siblings, so full sibling differentiation is left to inference.

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 rationale 'avoid rereading unchanged text' implies the delta-monitoring use case, and 'Supplied data only; no fetch' hints at when this is preferred over a live-fetch tool. However, there is no explicit when-to-use, when-not-to-use, or named alternative among the many sibling tools, leaving routing to inference.

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