campaign_estimateEstimate recipient count and SMS cost for a campaign before sending, so you can review audience size and budget without dispatching messages.
Number of recipients and SMS cost for a campaign. Sends nothing.
| Name | Required | Description | Default |
|---|---|---|---|
| body_short | Yes | SMS text | |
| recipients | Yes | Audience object, as in the campaign | |
| channel_priority | No | Channel order |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is largely covered. 'Sends nothing' usefully reinforces that no messages are dispatched, which matters for a campaign-named tool. But nothing is said about how cost is computed (segments, per-channel rates), what the response contains, or error behavior for malformed audiences.
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, front-loaded with the outputs and immediately followed by the key safety constraint. No filler or repetition of the schema.
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?
With no output schema and a nested, untyped recipients object, the description should explain the shape of the result (recipient count plus cost, possibly per channel) and how channel_priority influences pricing. It states the outputs at a high level but leaves enough gaps that an agent cannot fully predict the response.
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 100%, including descriptions for recipients, body_short, and channel_priority, so the schema carries parameter meaning. The description adds no extra semantics such as how channel_priority affects the cost estimate. Baseline 3 applies when the schema already documents every parameter.
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 the concrete outputs (recipient count and SMS cost) and the resource (a campaign), so an agent knows exactly what it gets back. It doesn't explicitly use an estimate/dry-run verb, but 'Sends nothing' disambiguates it from actual campaign sending. Sibling differentiation against campaign_sms_balance or campaign_details is only implicit.
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?
Usage is implied rather than stated: 'Sends nothing' suggests the natural pre-send pricing check, but the description never says when to call it, whether it is a prerequisite for campaign creation, or which sibling to use instead. No alternatives are named.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.