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

Adds substantial context beyond annotations: 7-day polling window, what an alert contains (added and removed text), the $0.005 USDC x402 payment requirement on Base, and the exact 402-with-requirements failure mode when unpaid. Annotations only cover safety/openWorld traits, so this payment/auth and lifecycle detail is genuinely additive.

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 core behavior and cost, and every sentence carries information. The free-alternative URLs are useful but slightly promotional and could be trimmed for tightness.

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 no output schema, the description still explains what alerts contain and the polling lifetime and payment path, which is what an agent needs to commit. It stops short of saying how alerts are retrieved (poll_alerts) or how the webhook interacts with polling as the primary delivery path.

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 url, webhook, and idempotency_key; the description adds nothing parameter-specific (no mention of webhook push vs polling tradeoff beyond what the schema says). Baseline 3 is appropriate.

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 ('Monitor a public web page') plus the key differentiator versus check_web_page/check_now: persistence 'between agent runs' with added/removed text on change. An agent can tell this apart from one-shot check siblings without opening a 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?

The 'between agent runs' framing clearly implies when to use this over a one-shot check, and it routes free/low-commitment users to /demo and /try. It never explicitly names the alternative siblings (check_web_page, create_watch, try_watch) or states when not to use this, so it's clear context but not full when/when-not guidance.

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