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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description adds genuinely useful context beyond them: the third-party backing service (HackerTarget) and the shape of what is returned (ASN, prefix, network name). It stops short of noting rate limits, availability risk, or failure behavior for that external dependency.

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-loaded with the three query intents an agent would match against, then mechanism, then use case — a sensible ordering with no filler. The three quoted phrasings are slightly redundant with one another, costing a little density but aiding retrieval.

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 one-parameter lookup with no output schema, the description covers what the tool does, what it returns, and when to reach for it, which is enough to invoke it correctly. It omits only secondary operational detail such as third-party rate limits or error behavior.

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% and the single 'target' parameter already documents IPv4-or-ASN syntax with examples, so the baseline is 3. The description reinforces that the input is an address but adds no format or edge-case detail beyond the schema (e.g. whether ASN input returns a different payload).

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: 'autonomous system lookup via HackerTarget', and names exactly what is returned (ASN, announced prefix, network name). The quoted user phrasings ('which ASN owns [IP]', 'who is the upstream provider') make it immediately distinguishable from sibling lookups like whois, geoip, reverse_ip and subnet_lookup.

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?

Gives a clear context of use: 'Use to attribute an address to a hosting provider, ISP or cloud region.' However, it never names the adjacent alternatives (whois, geoip, reverse_ip, subnet_lookup) that an agent might confuse it with, and states no exclusions or prerequisites, so routing among siblings is left to inference.

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