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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: the verdict is allow/block, findings carry a rule and severity, detection is rule/threat-list based, and quoted fragments of the scanned text are deliberately omitted from the answer.

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?

Two sentences, front-loaded with the action and mechanism, with the return shape and the output-omission caveat following. No filler or restatement of the title.

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 no output schema, the description carries the return-value burden and does so well: allow/block verdict plus per-finding rule and severity, and it explains why no quoted fragments appear. It stops short of noting limits on input size or how nested tool objects are traversed, 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 description coverage is 100%, so both 'tools' and 'server' are already documented in the schema. The description reinforces what is being scanned (name, description, schema, annotation) but adds no syntax, shape, or constraint detail beyond the schema, so the baseline 3 applies.

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 (Scan) and resource (an MCP server's tools/list) and names the detection mechanism (static rules + threat list over name, description, schema, annotation). It is unmistakable against siblings like histor_check, tool_list_cost, and x402_check, which address unrelated concerns.

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?

Usage is implied by the object of the scan (a server's tools/list result passed as input), so an agent can infer when to reach for it. However, there is no explicit when-to-use or when-not guidance and no named alternative, and the sibling list offers no near-twin to route away from.

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