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

Annotations only provide readOnlyHint=false, which is minimal. The description adds valuable behavioral context: the first call records a baseline and reports no change, snapshots are kept per page and tag, and two watchers on the same page do not consume each other's changes. It does not detail the diff format or how often checks can be made, but it covers the most important behavioral surprises.

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 compact and front-loaded: the core function is in the first sentence, followed by use cases, then the baseline caveat, then the tag guidance, then sibling routing. Every sentence earns its place and there is no filler.

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 tool with only 2 parameters, no output schema, and minimal annotations, the description covers the key context: what it does, when to use it, the baseline behavior, the tag semantics, and alternatives. It could mention what the diff looks like or whether the tool can be used on non-public pages, but these are minor gaps given the tool's simplicity.

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 the schema already documents both parameters well. The description adds meaning by explaining why the tag matters ('so two watchers on the same page do not consume each other's changes') and by framing the url as a public web page. This goes beyond the schema's field-level 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 states a specific verb and resource ('Check whether a public web page has changed since the last time this was called for it, and get the diff') and immediately distinguishes it from siblings like read_web_page and web_search. It also names the sibling it is not, which makes the tool's purpose unmistakable.

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 explicitly says when to use this tool ('Use for watching one page over time') and names alternatives with their conditions ('For the contents of a page use read_web_page; for the open web use web_search'). It also explains the first-call baseline behavior and the tag requirement, which are essential usage details.

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