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

Annotations already cover readOnlyHint and openWorldHint, and the description still adds substantial operational context beyond them: the payment model ($0.002 USDC per successful call via x402 on Base, Solana or Arc), the fact that failed calls are not charged, the data source (public CSMS feed), and the limitation that no live uptime meter exists. That is exactly the kind of costing and data-provenance information an agent needs.

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 front-loads the resource and return shape, then folds the pricing and data-source caveat in at the end. Most sentences earn their place, though the pricing/licensing sentence is dense and slightly inflates length relative to the core purpose.

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, the description need not describe return values in full, and it still names the returned fields and the unresolved-outage flag. Combined with 100% schema coverage on the two optional parameters, annotations signalling a read-only open-world call, and the explicit cost model, an agent has everything needed to invoke it correctly.

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 optional parameters, making 3 the baseline. The description adds the message categories, but its list (outage, delay, resolved, maintenance window, quota bulletin, HTS update, information) does not exactly match the schema's type options (outage, maintenance, resolved, quota, hts, information), which adds mild ambiguity rather than clarity.

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 (US Customs ACE system status from CBP's CSMS feed) and enumerates exactly what comes back: messages with number, date, title, link, type, plus an unresolved outage/delay flag. It is clearly distinguishable from sibling customs tools like customs_cbp_manifest or customs_duty_calc.

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?

Usage is clear from context: check ACE/ABI system health, outages, delays, maintenance windows. It also explicitly bounds expectations with 'CBP does not publish a live uptime meter,' which prevents misuse as a real-time uptime monitor. It does not explicitly name alternatives or state when not to use it, so it stops short of a 5.

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