trello-guardrails-mcp

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Create Label

create_label

Create a new label on a Trello board by specifying board name and label name, with an optional color from a predefined list.

Instructions

Create a new label on a Trello board. Color must be one of: yellow, purple, blue, red, green, orange, black, sky, pink, lime, or empty for no color.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "board_name": "<board_name>",
      "label_name": "<label_name>"
    },
    "name": "create_label"
  }
}

Input Schema

Name	Required	Description	Default
`color`	No
`board_name`	Yes
`label_name`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 25, 2026

TDQS

A3.5/5.0

Behavior3/5

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

With no annotations, the description carries the behavioral burden. It discloses the create operation and the valid color set, but it does not mention potential duplicate-label behavior, required permissions, or failure handling. This is adequate for a simple additive create tool but leaves some behavioral context unstated.

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?

Two short sentences with no filler. The core action is front-loaded, and the color constraint is the second essential piece of information. Nothing is redundant or wasteful.

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 simple 3-parameter create tool with an output schema, the description covers the only non-obvious input constraint (color values) and specifies the target resource (a Trello board). It lacks explicit sibling differentiation, but that is largely a usage-guidance concern rather than a completeness gap for invoking the tool correctly.

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?

Schema description coverage is 0%, so the description must add meaning. It provides the full valid color enumeration and clarifies that an empty string means no color. The other parameters, board_name and label_name, are reasonably self-explanatory given the tool's purpose.

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?

The description clearly states the verb ('Create'), the resource ('a new label'), and the scope ('on a Trello board'). It is distinct from sibling create_card/create_list, though it does not explicitly differentiate itself from the similarly named add_label.

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

Usage Guidelines2/5

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

No guidance is given about when to use this tool versus alternatives such as add_label, which likely serves a different purpose (e.g., attaching an existing label to a card). The intended usage is only implied by the tool's name and generic create phrasing.

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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