Infrastructure History

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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, yet the description adds material context beyond them: no API key required, rate-limited, the precise observation sources and the daily re-resolution caveat, plus the shape of the return (per-kind value timelines and a coverage note). This is unusually rich disclosure for a read-only tool.

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 purpose, then usage routing, then coverage limits — well ordered and free of filler. It is dense with many clauses in one long sentence, but each clause carries distinct, useful information, so sizing is justified though not maximally tight.

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?

An output schema exists, so return values need not be detailed, and the description still sketches them (per-kind timelines + coverage note). Combined with explicit coverage limitations, safety/rate-limit notes, and alternative-tool routing, 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 'target' parameter already documents domain/IPv4 format and stripping behavior. The description only echoes that it accepts a domain or IPv4 address, adding no syntax or format detail beyond the schema, so the 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+resource: it shows how a domain's or IPv4's infrastructure has changed over time, and enumerates the exact observation kinds (nameservers, A/AAAA, MX, CNAME, cert issuer, registrar, RDAP, ASN/PTR). It also distinguishes itself from dns_lookup and rdap_lookup, so an agent can route between them without opening schemas.

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?

Explicitly scopes usage to past-tense questions with concrete examples ('when did the nameservers change?', 'which IPs has it used?') and names the alternatives (dns_lookup, rdap_lookup) for current state. It also states the coverage boundary — only DechoNet's own observations, not full passive DNS — which is exactly the when-not guidance an agent needs.

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