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

Annotations already declare readOnly/openWorld=false/idempotent, but the description adds substantial context beyond them: a 30 calls/day free tier shared across all three scan tools, a 10/min cap, invalid input not counted, and a documented x402 fallback with price, chains and URL. It also discloses the return payload fields and honestly frames output as a safety signal, not a guarantee. The only thing left implicit is latency/behavior on partial failures.

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 purpose, then alternatives, then limits, then return shape — a sensible information order. It is dense, however: rate-limit, pricing and return-shape details are packed into one long paragraph where a few of the clauses (invalid-input accounting, full URL) could be trimmed.

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 single-parameter, no-output-schema tool, the description covers everything an agent needs: what is scanned, limits, failure/payment path, response fields and the caveat that the verdict is not a guarantee. Nothing actionable is missing.

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 schema description already explains the 1-100 object shape plus the name/description/inputSchema key handling. The description's 'Up to 100 tools per call' largely restates the schema's '1-100' bound, adding no format or edge-case meaning. Baseline 3 is appropriate when 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?

States a specific verb and resource — checks MCP/function-calling tool definitions for tool poisoning — and enumerates the vectors it looks for (hidden instructions, exfiltration, name/description/schema hijacks). It also explicitly separates itself from scan_text and scan_url, so an agent can route without opening any schema.

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?

Gives the exact decision rule: use this on tool definitions before installing or calling them, use scan_text for ordinary content, scan_url for web pages. Alternatives and selection conditions are both named, leaving nothing to inference.

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