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

Annotations mark this as non-read-only, non-idempotent, and open-world, and the description justifies all three: it discloses that eligible CSI observations may be persisted best-effort, that results are point-in-time, and that an empty result is not proof of absence. That is real value beyond the annotations, though the persistence side effect is stated twice rather than expanded (e.g. failure handling).

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 the core action, then caveats, then routing rules — good ordering. It loses a point for redundancy: the "eligible CSI observations may be persisted best-effort" sentence is repeated almost verbatim, and the bold section labels add visual noise without information.

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?

With an output schema present, the description needn't detail return fields, and it instead covers the things structured data cannot: point-in-time semantics, the false-negative risk of empty results, and the persistence side effect. An agent has everything needed to call this correctly and interpret the result honestly.

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 already constrains the single domain parameter precisely (bare hostname, no protocol/path, localhost and IPs rejected). The description adds a genuinely non-obvious disambiguation: domain is the customer domain to inspect, not a vendor domain — a distinction the schema cannot express.

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 ("Scan a customer domain to detect vendors and technologies") plus the mechanism (deterministic fingerprints) and the return content (technologies with supporting evidence). It is clearly distinguishable from the vendor-customer lookup siblings, which answer different questions about the same entities.

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?

Explicit USE WHEN and DO NOT USE WHEN blocks name three alternative tools and the exact condition that routes to each (confirmed customer base, historical adoption/removal events, transition signals). Nothing about tool selection is left to inference.

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