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

Annotations only say it is a non-read-only, closed-world operation; the description adds the real behavior an agent needs: pricing (testers x 15 credits), escrow hold, and that unused credits are returned to the balance in credits rather than money. It does not cover what happens on failure, duplicate campaigns, or cancellation/refund effects, which keeps it from a 5.

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 tight sentences with zero filler; the core action comes first and cost/escrow follows. '(needs a token)' is terse to the point of being cryptic, but it earns its place as an auth warning.

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 mutating tool with no output schema, the description covers cost, escrow, refund, and auth well, but omits what the call returns (e.g., a campaign identifier an agent would need for campaign_report or set_campaign_status), leaving a meaningful 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 coverage is 50%: package_name is documented in the schema, while testers has only default/min/max constraints. The description adds genuinely new meaning by tying testers to a cost formula, but never mentions the default of 15, the 12-30 range, or that package_name must belong to the user's own app.

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: 'Start recruiting a set number of testers for one of the user's apps.' It is distinguishable from set_campaign_status and start_friends_test by the recruiting-plus-cost framing, though it never names a sibling 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?

Implies usage ('start recruiting') and hints at a prerequisite with '(needs a token)', but gives no guidance on when to choose this over start_friends_test, add_testers, or set_campaign_status, and no exclusions or preconditions beyond auth.

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