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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered, but the description adds genuinely non-obvious operational context: it is paid-only, costs 5 prepaid credits, and requires production billing. It does not disclose what a detection result looks like, whether it fails or reports, or any thresholds for a "gap".

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, both load-bearing: the detection scope is front-loaded and the billing constraint follows. Nothing is redundant or padded.

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 one-parameter read-only tool with no output schema, the definition still leaves the agent guessing about the input element format and the shape of the result (list of gaps? boolean? indices?). The billing disclosure is a strong addition, but the core input/output contract is under-specified.

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 0% for the single required parameter "sequences" (typed only as array), so the description must carry the burden. It implies the array holds sequence numbers from an event stream, but does not state the element type (integers vs. event objects), required ordering, or any size limits.

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 names a specific verb ("Detect") and two specific defect classes (non-monotonic sequence numbers and gaps) over a clearly scoped input ("a supplied event stream"). This distinguishes it in substance from siblings like duplicate-events or nonce-replay checks, though it never names an alternative explicitly.

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?

There is no statement of when to choose this over the many adjacent integrity/ordering siblings (e.g. duplicate-events, dependency-order, nonce-replay-window), nor any exclusions or prerequisites beyond the billing note. The implied usage is only that the caller has an event stream; the agent must infer the rest.

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