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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered; the description adds real value beyond that by disclosing the hit payload ('date added and the malware reason'), the coverage limitation, and pricing/billing semantics ($0.002 USDC per successful call via x402 across Base, Solana or Arc, with failed calls uncharged). That payment and coverage detail is not derivable from any structured field. It stops short of describing miss behavior or latency, keeping it at 4.

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?

Four short sentences, front-loaded with the verb and data source; return shape, coverage caveat, and cost follow in priority order. No sentence is redundant or padded.

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 an output schema and readOnly annotations, the description supplies everything an agent needs: what is queried, what a hit yields, the list's coverage limit, and the metered cost. Nothing material is missing for correct invocation.

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's schema description already states 'Certificate SHA-1 fingerprint, 40 hex characters (required)'. The tool description repeats the same 40-hex format constraint but adds no parsing or normalization guidance (e.g., uppercase vs colon-separated formatting), 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 ('Checks a certificate SHA-1 fingerprint against the abuse.ch SSL Blacklist of certificates seen on malware botnet C2 servers'), naming the exact data source and threat category. This cleanly separates it from siblings like security_cert_revocation_crl, security_ssl_cert_chain, and security_crtsh_transparency, which concern revocation, chain validation, and CT logs rather than a malware blacklist.

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 sentence 'Only certificates this list tracks are covered' implies the tool's scope (blacklisted C2 certs) and warns of false-negative risk, which is useful context. However, it never says when an agent should prefer this over the sibling cert/blacklist tools or what to do with a non-hit, leaving usage inference to the reader.

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