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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond that: it clarifies that these are measurements, not accusations of intent, and that each anomaly carries an on-chain reference on Base, which shapes expectations about data provenance and tone. It also notes the service is free, which is a usage condition. No contradiction with annotations.

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 informative and well-organized, starting with the core purpose and then expanding with specific examples and a safety note. It is somewhat verbose—the list of anomaly types could be trimmed, and 'Free' at the end is minor—but every sentence adds context about what the tool reports and why it matters. The front-loading of the main clause is effective, so a 4 is justified.

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 read-only incident listing with no output schema, the description adequately conveys the nature of returned data: anomalies with on-chain references on Base. It also includes a practical warning ('Check before paying anything') that guides agent behavior. While it does not specify the exact output structure (e.g., field names), the description gives enough context for an agent to know what to expect and when to use it. Slightly more detail on return format would push it to a 5, but this is sufficient.

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 only parameter 'days' is fully described in the schema (default 30, min/max), giving 100% schema description coverage. The tool description does not mention this parameter at all, so it adds no additional meaning beyond what the schema already provides. Baseline 3 is appropriate because the schema carries the burden and does so completely.

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 opens with a clear, specific verb and resource: 'Anomalies observed in live x402 endpoints by continuous independent measurement,' immediately differentiating this tool from generic incident lists. It enumerates concrete anomaly types (receiver-address changes, price mismatches, invalid receivers, etc.) and adds a distinctive framing ('Measurements, not accusations of intent'), making the purpose unmistakable even without sibling names.

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 provides an explicit usage cue: 'Check before paying anything,' which tells the agent when to invoke this tool (before payment decisions). It does not name alternative tools or state exclusions, but the context is clear and the directive is actionable. Sibling tools like check_x402_endpoint or mcp_security_report are not referenced, so a slight deduction for lack of explicit routing.

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