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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds material context beyond them: the data is from cached published lists, the cost is $0.01 USDC per successful call via x402 on Solana, and an equivalent HTTPS endpoint is given. That price/payment disclosure is exactly the kind of behavioral fact an agent needs before calling.

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?

Scope and list coverage are front-loaded, followed by the disambiguation and then practical details (price, endpoint). Dense but each clause carries information; the separately appended HTTPS endpoint is slightly tacked-on rather than integrated.

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 compensates by describing the return payload (matched range/SBL reference, categories, 0-100 risk score). Combined with pricing, input limits, and the sibling boundary, an agent has everything needed to call 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 coverage is 100% and the single parameter already documents comma-separated input, the max-50 limit, and the 'ips' alias. The description only restates the 50-address cap and adds that IPv6 is accepted; useful but marginal over structured data, so baseline 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?

States a specific verb-and-resource pair: blocklist reputation for up to 50 IPv4/IPv6 addresses, then enumerates the exact lists checked (Tor exit, Spamhaus DROP/DROPv6, Feodo C2, FireHOL level1). It explicitly distinguishes itself from the geo/ASN sibling by noting 'Blocklist membership only; complements /v1/ip-intel'.

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 clearly scopes usage ('blocklist membership only') and routes the agent elsewhere for geo/ASN via ip-intel, which is the main disambiguation an agent needs against ip_intel/phishing_score. It stops short of explicit when-not guidance (e.g. no note on single-IP lookups or fallback to plain ip_intel when only geo is required).

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