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

Goes well beyond the annotations by disclosing the stateful baseline behavior ('the first call records a baseline and reports no change, which is normal') and per-page/per-tag snapshot isolation. It never claims read-only, so the destructiveHint=true annotation is not contradicted, but it also does not explain what that hint refers to (persisting/replacing a stored snapshot), which is the one behavioral fact left uncovered.

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-loaded with the core action and result, then use cases, then the baseline caveat, then sibling routing — four short sentences, no filler, nothing repeated from the schema verbatim.

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?

There is no output schema, and the description covers the key return signals ('changed or not' plus 'the diff') and the baseline edge case, which is enough to call it correctly. Minor gaps: diff format/size and what a snapshot overwrite means under destructiveHint are not described.

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%, so parameter definitions already exist, yet the description adds operational meaning: pass your own agent id as `tag` so two watchers on the same page 'do not consume each other's changes.' That is a real usage rule the schema only hints at, not a restatement.

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 ('check whether a public web page has changed') plus the payoff ('get the diff'), and contrasts with read_web_page and web_search. An agent can distinguish this from the adjacent page-reading and search tools without opening any 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?

Names the concrete use case family ('watching one page over time: team page, pricing page, careers page') and gives explicit routing to two alternatives: read_web_page for contents, web_search for the open web. It also sets expectations for the first call so the agent does not misread a no-change baseline as a failure.

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