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

Annotations only indicate a mutating, non-idempotent operation, but the description discloses the important behavioral details: it debits the wallet for SMS cost plus any curated owner payout, queues delivery, and returns a 402 with shortfall details on insufficient balance. This reveals financial side effects and a failure mode beyond what annotations or schema provide, with no contradiction.

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?

Three sentences each carry distinct value: the action, the financial and queueing behavior, and the insufficient-balance remediation. It is front-loaded and contains no filler.

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 tool with no output schema, the description covers the action, side effects, and the key failure mode well. It does not describe the success return value or suggest estimating costs first, but these are minor gaps given the simple schema and rich behavioral description already present.

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?

The schema already documents campaignId fully as the UUID of the draft SMS campaign to send, with 100% coverage. The description reiterates the draft status but adds no new parameter-level detail such as format constraints or how to obtain the campaign ID.

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 specifically that it sends a draft SMS campaign, identifying a distinct lifecycle action among the many sms_campaign siblings (create, estimate, get, pause, resume, delete, list). The verb 'Send' plus the 'draft' precondition clearly distinguishes this from other campaign-related tools.

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?

Clearly signals the precondition that the campaign must be a draft and gives a concrete recovery path for the 402 case by naming neuron_fund_wallet. It does not explicitly enumerate alternatives such as neuron_estimate_sms_campaign or state when not to send, so it falls just short of full routing guidance.

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