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

Annotations already declare this a safe, closed-world read (readOnlyHint=true, openWorldHint=false), so the description does not need to establish safety. It does add genuinely useful behavioral context that the annotations cannot: this is a paid call costing 5 prepaid credits and requiring production billing, which matters before invocation. It stops short of describing what the evaluation returns (a boolean recommendation? a reason code?) or what happens when credits are exhausted.

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 short sentences with the substantive purpose front-loaded and the billing constraint immediately after; no filler or restatement of the title. Slightly abrupt, but every sentence carries information an agent needs before calling.

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 three-parameter, no-output-schema evaluation tool, the description covers the core decision it makes and the material operational constraint (paid, billed, prepaid credits). What is missing is the semantics of individual parameters, which is a parameter-level gap already reflected there rather than a failure of overall completeness. The definition gives an agent enough to decide whether to invoke it and how to frame the call.

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% across three required parameters, so the description carries the full explanatory burden and largely fails to meet it. The phrase 'failure threshold' loosely gestures at the threshold and consecutive_failures inputs, but nothing explains units, valid ranges, or what cooldown_elapsed controls — an agent must guess whether the cooldown is a fixed window or a caller-supplied boolean condition.

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 states a specific verb and decision: evaluate whether a failure threshold requires blocking new requests. That is clearly distinguishable from a generic utility, but it never clarifies how it relates to the similarly-named sibling privi_circuit_decide (does this produce a recommendation while that one makes the call?), so the boundary between the two is left to inference.

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 when-to-use guidance, no prerequisites beyond the billing note, and no statement of when an agent should prefer privi_circuit_decide or any other circuit-related tool. The only qualifying information is a cost warning, which segments usage by billing status rather than by task.

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