Commerce for Agents

Compare US Mobile Phone Plans

compare-mobile-plans

Read-onlyIdempotent

Ranks US mobile/cell phone plans (postpaid carriers AT&T/Verizon/T-Mobile and prepaid MVNOs like Mint, Visible, Cricket, Metro, Google Fi, US Mobile, Tello, Boost, Straight Talk, Xfinity Mobile) by 12-month average cost per line (curated, verified catalog; not the whole market). Keywords: cell phone plan, mobile plan comparison, unlimited data plan, family plan, prepaid vs postpaid, best phone plan. Input: number of lines and optional data need, budget per line, prepaid/postpaid preference, must-haves (hotspot, 5g, premium_data, unlimited_data), and preferred network. No address or location is collected — this tool does not check coverage; tell the user to confirm coverage on the carrier's site.

Input Schema

TableJSON Schema

Name	Required	Description
`lines`	No	Number of phone lines to price.
`data_need`	No	Minimum data: light ≥2GB, moderate ≥5GB, heavy ≥20GB, unlimited = unlimited plans only.
`must_haves`	No	Required features: hotspot, 5g, premium_data (deprioritization-free), unlimited_data.
`budget_per_line`	No	Max USD/month per line.
`preferred_network`	No	Preferred underlying network, e.g. AT&T, Verizon, T-Mobile.
`prepaid_or_postpaid`	No	Restrict to prepaid or postpaid plans; omit for both.

Output Schema

TableJSON Schema

Name	Required	Description
`lines`	Yes
`plans`	Yes
`source`	Yes
`message`	No
`priceNote`	Yes
`coverageNote`	Yes
`selectionNote`	Yes	Curated selection of N plans from M providers, not the whole market.
`catalogPlanCount`	Yes
`oldestVerifiedDate`	No	Oldest verified_date among the plans shown.
`catalogProviderCount`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 26, 2026

removedInput schema / properties / context

Removed value: -{
-  "description": "Why are you calling this tool? Briefly describe the user's goal.",
-  "type": "string"
-}

removedInput schema / required
```
Removed value: -[
-  "context"
-]
```

AddedSep 26, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Annotations already declare readOnlyHint=true and idempotentHint=true. The description adds substantial behavioral context beyond that: the catalog is 'curated, verified' rather than the whole market, it ranks by 12-month average cost, and it does not check coverage or collect location. This fully informs the agent of important limitations.

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?

The main purpose and critical caveat are front-loaded, and the structure is logical: purpose, scope, input summary, limitation. The keyword sentence ('cell phone plan, mobile plan comparison...') adds bulk and is not behaviorally useful for an AI agent, preventing a 5.

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

Completeness5/5

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

With six optional parameters, high schema coverage, and an output schema present, the description covers everything an agent needs: what is ranked, included carriers, ranking basis, filter inputs, and the important no-coverage-check limitation with a user-facing action. Nothing critical is missing.

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 description coverage is 100%, so the baseline is 3. The description briefly mentions inputs like 'number of lines,' 'data need,' 'budget per line,' and 'must-haves,' but it adds no meaning beyond what the schema already documents for each parameter.

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

Purpose5/5

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

The description opens with a specific verb and resource: 'Ranks US mobile/cell phone plans... by 12-month average cost per line.' It lists the exact carriers and MVNOs covered, which clearly separates it from siblings like compare-broadband and compare-tariffs.

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

Usage Guidelines4/5

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

The description gives clear context for when to use the tool: comparing US mobile plans with optional filters. It also provides an explicit post-use instruction ('tell the user to confirm coverage on the carrier's site') and states the catalog is curated. It does not explicitly name sibling alternatives or exclusion conditions, so it falls just short of a 5.

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

All Commerce for Agents tools Inspect

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

Need Help?