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

No annotations are present, so the description carries the full burden. It does disclose a significant behavioral trait: 'Costs $0.003 USDC (x402, Base),' which alerts the agent that calling this tool triggers a payment. However, it does not mention what happens on invalid URLs, whether the tool makes an outbound request to the target site, the response format, or any rate limits.

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 compact and front-loaded with the core action, followed by useful category examples, a use-case phrase, and the cost. Every sentence adds value: what it detects, why to use it, and what it costs. No filler or 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?

For a one-parameter tool with no output schema and no annotations, the description covers the main purpose, use cases, cost, and detection categories. However, it omits any indication of the output format or the behavior of the tool (e.g., whether it returns a report, errors on non-http(s) URLs, or how the cost is billed). This leaves the agent without a full picture of what the call returns.

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?

The schema covers the sole parameter (url) with a description 'Public http(s) URL' and 100% coverage, so the baseline is 3. The tool description adds no additional meaning beyond the schema, merely implying the URL through 'website.' There is no need to compensate for coverage gaps.

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 names the verb and resource: 'Detect the technology stack of a website' and then enumerates specific categories (frameworks, CMS, analytics, payments, CDN/hosting, server headers). This makes the tool's function specific and distinct from siblings like check_email_domain or extract_webpage in substance, though it doesn't explicitly name those alternatives.

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 provides explicit use contexts: 'Useful for lead qualification and competitor research.' This gives clear guidance on when to invoke the tool. It does not, however, state when not to use it or explicitly compare it to sibling tools, so it's one step short of full differentiation.

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