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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true, covering the safety profile. The description adds the key behavioral trait that it fans out across four data sources in one call, but does not disclose latency implications, rate limits, or whether partial failures are possible.

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?

Two tight sentences: the first front-loads what the tool returns and the sources it combines, the second delivers usage guidance. No filler, no redundancy.

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-value explanation is unnecessary, and the description correctly focuses on what data categories are combined and when to use it. It is complete enough for confident invocation; missing only handling of partial failures or whether dedicated sibling tools return richer data.

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% with a single, simply documented parameter (domain with example 'stripe.com'). The description reinforces the input being a domain but adds no new formatting or syntax detail beyond the schema, and with only one parameter at full coverage a baseline of 4 is appropriate.

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?

The description states a specific verb and resource ('full dossier on a domain') and enumerates exactly what is aggregated: RDAP registration, DNS records, email deliverability, and tech stack. This explicitly distinguishes it from the siblings dns_lookup, email_deliverability, and tech_stack by positioning itself as the combined one-call alternative.

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 states clear use cases (lead qualification, company research, recon) and implicitly routes the agent away from the four separate sibling calls. However, it does not specify when NOT to use it – e.g., when only one data type is needed, or whether dedicated tools offer deeper/more complete results. Explicit exclusions would raise this to a 5.

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