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 usefully adds the fail-closed posture, the freshness requirement on the counter, and the 0.002 USDC cost, which annotations do not convey. It stops short of saying what a denial looks like or whether the call itself performs the slot reservation.

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?

A single dense sentence that front-loads the failure condition and appends the price. Nothing is wasted, though the compression is extreme enough to obscure the tool's core action.

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 7-required-parameter guard with no output schema and no field descriptions, the definition is thin: it does not explain how active_slots plus requested_slots are compared against policy.maximum_slots, nor what the caller receives on pass versus fail-closed.

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 7 required parameters, so the description carries the full burden. It loosely hints at three parameter clusters (counter freshness → counter_observed_at, lease → lease_id/lease_valid_until, idempotency binding → idempotency_key) but leaves requested_slots, active_slots, and policy.maximum_slots unexplained, and never states the freshness window or timestamp units.

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 decision policy ('fail closed unless...') and the inputs that gate it (fresh counter, lease, idempotency binding) plus a price, so the resource is identifiable. However, it never states the tool's overall function in plain terms (e.g., admit/deny a request against a concurrency cap), and it does not distinguish itself from close siblings such as idempotency_replay_guard or resource_cycle_guard.

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, and no named alternative. Given the dense set of guard siblings (idempotency_replay_guard, resource_cycle_guard, delegation_scope_guard), the agent has no signal for choosing this one over them.

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