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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the description's real contribution is the consequence ('can no longer be treated as unseen'), the audit recording, and the owner-only/paid gate — genuinely useful beyond the structured hints. It stops short of saying whether a second call errors out or whether the reveal payload comes back in the response, which matters for a destructive one-shot action.

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?

Four short sentences, front-loaded with the irreversible action and its consequence, with prerequisites and scope following. The closing access note ('keyless: subscription_required with a subscribe link') is terse to the point of being jargon-heavy, but nothing is padding.

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 destructive action with annotations and no output schema, the definition covers irreversibility, cost, ownership, and scope of effects. The only real gap is what the agent gets back on success and how repeat invocation behaves, which is not covered by annotations or an output schema.

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?

With 100% schema description coverage, the single run_id parameter is already fully documented as a 32-hex study ID from an owned run result. The description adds no additional meaning about the identifier or its provenance beyond the schema baseline, so this is the expected 3.

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 ('expose a study holdout') plus the side effect ('record its exposure'). An agent can distinguish it from research_run_read or research_run_submit without opening a schema, because the irreversibility is stated in the first sentence.

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?

Gives clear preconditions and boundaries: paid, owner-only, and explicitly 'No live orders or model inference.' It implies this is a deliberate terminal step after a run exists, but it never names a sibling alternative (e.g., read the run without revealing) or says what to do if the holdout was already revealed.

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