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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, and the description still adds real context: a 500-address cap, twice-daily list refresh, no API key, and the interpretive caveat that 'being on a list is evidence, not proof'. Those freshness and rate-limit facts are exactly the kind of trait annotations cannot express. It omits any hint of response shape beyond private-range labelling.

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 core action and scope, then limits and caveats; the trailing no-key and evidence-not-proof notes are short and useful. The parenthetical enumeration of all 12 blocklists is longer than strictly necessary but does inform trust decisions, so it earns its place—barely.

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 single-parameter read tool with no output schema, the description covers sources, input forms, batching limit, data freshness, and the special-range exception, which is close to enough to call it correctly. The main gap is that it never sketches what a result entry looks like, leaving the agent to infer the per-address verdict format.

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% for the single 'text' parameter, so the baseline is 3. The description earns the extra point by expanding what 'text' tolerates (raw addresses, log lines, CSV) and adding the 500-address ceiling, which materially affects how the agent batches a call.

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 IPv4 addresses against 12 free public blocklists') and names the exact data sources, so an agent can distinguish it from analyze_log_file or scan_log_for_attacks without opening a schema. The named list set and the reference to logtriage.app ground what the tool actually does.

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?

Clear about input flexibility ('a list of addresses or any text containing them (log lines, CSV)') and about scope boundaries ('private and other special-purpose ranges are labelled, not looked up'), which tells the agent what inputs are wasted. It does not explicitly name a sibling or say when to prefer this over scan_log_for_attacks, so it stops short of full alternative routing.

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