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

No annotations are provided, so the description carries the full burden. It does disclose a key behavioral trait: payment of $0.001 USDC via x402, which is a significant cost consideration. However, it doesn't mention return format, error handling, or whether the operation is read-only, leaving some gaps.

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 two sentences, front-loaded with the core purpose, and the second sentence conveys essential cost information. No fluff or irrelevant details.

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 covers the main function and the payment requirement. It implies the output is a list of unique URLs but doesn't explicitly state it or handle edge cases, which is a minor gap.

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% because the only parameter 'text' is fully described. The description's phrase 'arbitrary text' adds little beyond the schema's 'Text to extract URLs from.' Baseline of 3 applies since the schema does the heavy lifting.

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 the tool's function: 'Extract all unique http(s) URLs from arbitrary text.' It uses a specific verb ('extract') and resource ('URLs'), and its purpose is distinct from sibling tools (crypto market data, DNS lookup, JSON repair).

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 clear context for use (extracting URLs from any text), and the sibling tools are obviously different, implying when to choose this tool. However, it does not explicitly state exclusions or alternatives, so it stops short of a 5.

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