Skip to main content
Glama
Sign In

Hailbell

by com.hailbell.api
OverviewDiscussionsAdmin

estimate_audience

Read-only

Counts the devices an audience reaches, per platform and per App ID (byApp), and the people they belong to, without sending anything.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "estimate_audience"
  }
}

Input Schema

NameRequiredDescriptionDefault
kindNoDefault marketing
appIdNoThe app to act on, from list_apps. Optional when the key belongs to one app.
audienceNoWho receives it. Empty means every subscribed device of the app.
platformsNoSeveral platforms of one app in one campaign: "all", or a list of "ios", "android", "web" (or App IDs). Each person gets it once. Omit (with no productId) for the one platform of appId.
productIdNoThe whole app (productId from list_apps), for a campaign across its platforms. Same as appId of any platform with platforms "all".

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • changedInput schema / properties / audience / properties / externalIds / description
      Previous value: -"Your own user ids, as the app passed to Hailbell's identify"New value: +"User ids: the id the app signs in to Hailbell with, or the Superwall user id, Superwall alias id or RevenueCat id it sends as metadata (as on the customer's sheet)"
  2. First observed

TDQS

A3.7/5.0
Behavior4/5

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

The readOnlyHint/openWorldHint annotations already establish the safety profile, so the description only needs to add context — and it does, by disclosing the shape of the result (per-platform and per-App-ID device counts plus person counts) and reinforcing that nothing is dispatched. It omits any note on cost, latency, or how aggregation is grouped in the response.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence with no filler, and the important contrast ('without sending anything') lands at the end. Minor deduction for the unexplained '(byApp)' aside, which adds a term the reader must decode rather than clarity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only estimation tool with a rich nested schema and no output schema, the description covers the essential question (what is counted, at what granularity, and that nothing is sent). What remains missing is guidance on default behavior and volume/cost implications, but the schema fills most of the semantic gaps.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with detailed per-field semantics (relations, platforms, audience defaults), so the schema carries the parameter burden. The description adds only the high-level notion of an 'audience' and no extra meaning for kind, productId, or the appId/productId interaction. Baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a concrete verb and resource: 'Counts the devices an audience reaches ... and the people they belong to'. The scoping detail 'per platform and per App ID (byApp)' further narrows what is produced. It falls short of a 5 because it never names the sibling it contrasts with (preview_notification) and the 'byApp' jargon is left undefined.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

'without sending anything' implies this is a sizing/dry-run tool to be used instead of an actual send, but the description never states when to pick it over preview_notification or coming_up, and gives no prerequisites. Usage is inferable rather than prescribed.

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

All Hailbell toolsInspect
Try in Browser
One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources