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

With annotations already declaring destructiveness and open-world behavior, the description adds substantial context: the $0.005 USDC x402 cost on Base, no API key or account needed, the 402 response with payment requirements when unpaid, that creation includes the baseline plus 7 days of polling, and that a webhook is optional while polling still works. This is exactly the pricing/auth/failure-mode detail annotations cannot express.

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?

Purpose and persistence contract are front-loaded, then the type requirements, then cost — a sensible order with no repeated content. The closing free-alternative sentence is longer than strictly necessary and reads slightly promotional, but it does carry actionable routing information for wallet-less agents.

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 16-parameter, nested, destructive, paid mutation tool with no output schema, the description supplies the pricing model, the payment failure mode, the id persistence contract, the polling handoff, and the per-type required fields. An agent can select and invoke it without further exploration; the remaining gap (alert payload shape) is covered by the sibling poll_alerts.

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 the baseline is 3, but the description earns more by stating conditional requirements the schema cannot express: url/rss/x402 need url, price needs coin plus a threshold, edgar needs ticker or cik. That cross-parameter rule is the single most useful thing an agent needs before building the call, and it is not derivable from the per-field schema text.

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 opens with a concrete verb and resource — 'Keep watching a source between agent runs and alert when it changes' — which clearly frames this as a persistent watch rather than a one-shot check. It never names the sibling check_* tools (check_web_page, check_sec_filings) or watch_* variants to explain when this generic creator is preferred over the typed ones, so differentiation is implied by 'between agent runs' rather than stated.

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 says when to use the tool (persistent monitoring across agent runs) and names the follow-up flow: persist watch_id, then poll_alerts with since=<last cursor>. It also gives concrete free alternatives (demo endpoint, try endpoint / try_watch) for agents without a wallet. What's missing is guidance on when to choose create_watch versus the typed siblings like watch_web_page or watch_crypto_price.

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