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

Adds substantial context beyond the annotations: refusal of private hosts (not charged), typical latency under 1 s, first check within ~10 minutes, USD 0.01 with no free tier, webhook signing via notify_secret, and notify_url retention/privacy. There is mild tension with readOnlyHint=true since the tool provisions a persistent scheduled watch and emits webhook POSTs, but it does not modify caller-owned resources, so this is not an outright contradiction; it should have clarified the watch lifetime/quota more explicitly.

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 assertion/webhook/pricing/latency facts are front-loaded and each sentence carries information, including a useful untrusted-data warning. The ambiguous 'Returns 20 scheduled checks' clause and the bare docs URL are the only lines that don't clearly earn their place.

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?

With an output schema present, return values needn't be explained, and the description still covers cost, latency, minimum cadence implications, webhook delivery semantics, and the follow-up read tool. It omits watch lifetime/quota and what a 'changed verdict' payload looks like, leaving a small but real gap for an agent planning the call.

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 every parameter (url, expect assertions, status, notify_url, every_minutes) is already documented in the schema. The description only restates 'optional webhook on change' and 'JSON-path or CSS assertions', adding no format or constraint detail beyond the schema, so the baseline of 3 applies.

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 core resource is specific (a scheduled read-back watch asserting a page/JSON answer for one HTTPS URL), but the opening sentence never uses the verb 'create' and instead says 'Returns 20 scheduled checks of one public HTTPS URL', which reads like a listing operation and blurs the line with the sibling get_readback_watch. An agent has to infer that this tool provisions a watch rather than fetching existing ones, despite the later routing sentence.

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?

It explicitly routes result retrieval to get_readback_watch, states that private/unresolvable hosts are refused, and gives cost and pricing tier, which shapes whether to call it. There is no explicit 'when not to use' compared with other monitoring siblings (e.g. get_endpoint_uptime), so it stops short of a full routing rule.

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