renfield-mcp-tracking

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list_carriers

Lists supported carriers and their configuration status, showing which are usable and whether they need credentials or return tracking links.

Instructions

List supported carriers and whether each is configured/usable.

'api' carriers need credentials (configured=False means missing keys). 'link' carriers always work but only return a web tracking link.

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": "list_carriers"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jun 18, 2026

TDQS

A4.7/5.0

Behavior5/5

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

The description fully discloses the tool's behavior: it returns a list of carriers with a flag indicating whether each is configured and usable. It explains the meaning of 'configured=False' for api carriers and that link carriers always work. No side effects are mentioned, which is appropriate for a read-only listing operation.

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

Conciseness5/5

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

The description is extremely concise: two focused sentences plus an additional clarifying line. It is front-loaded with the primary purpose, and every sentence provides essential information without redundancy.

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?

Given the tool has no parameters and an output schema exists, the description sufficiently explains what the tool returns (list of carriers with configuration status) and interprets the status values. This is complete for an agent to understand the tool's output.

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

Parameters4/5

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

The tool has no parameters, so the description does not need to add meaning beyond the schema. Per guidelines, 0 parameters yields a baseline of 4. The description adds value by explaining the output semantics.

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 clearly states the primary function: listing supported carriers and their configuration status. It distinguishes between 'api' and 'link' carriers, providing specific details that differentiate this tool from its siblings (detect_carrier, track_parcel).

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 explains when to use the tool (to see available carriers and their usability) and provides context about credential requirements for 'api' carriers. However, it does not explicitly state when not to use it or mention alternative tools, though the context is implied.

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

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