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

With no annotations, the description carries the full burden. It discloses that the analysis is heuristic (not definitive) and returns a risk level with a signal list, but does not elaborate on limitations, edge cases, or how signals are generated. Still, it adds useful context beyond a bare statement.

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?

The description is a single, front-loaded sentence that conveys the tool's core function and output without waste. Every word earns its place.

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 simple one-parameter tool with no output schema, the description sufficiently explains what the tool returns (risk level and signal list) and its heuristic nature. It lacks deeper caveats or comparisons to siblings, but given the low complexity, it is nearly complete.

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 0%, so the description must compensate. Although it does not explicitly mention the 'domain' parameter, the tool's purpose inherently implies the domain is the subject of analysis. This partial compensation is sufficient given the parameter is self-evident.

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 clearly states that this tool performs heuristic phishing/suspicious-domain signal analysis and specifies its output (risk level and signal list). It distinguishes itself from siblings like dns_lookup and security_headers by focusing on phishing risk assessment.

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 description implies usage for phishing/suspicious-domain evaluation, but provides no explicit guidance on when to use this tool versus alternatives like full_report or security_headers. There are no exclusions or alternative recommendations.

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