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Trello MCP Server

Trello MCP Server

by GabrielRamirez
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Hybrid

Add Attachment

add_attachment

Add a URL attachment to a Trello card to provide supplemental resources or references. Specify the card ID and the URL, with an optional display name.

Instructions

Add a URL attachment to a Trello card.

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": {
      "cardId": "<cardId>",
      "url": "<url>"
    },
    "name": "add_attachment"
  }
}

Input Schema

NameRequiredDescriptionDefault
urlYesThe URL to attach
nameNoDisplay name for the attachment
cardIdYesThe ID of the card

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv1.2.0

TDQS

B3.3/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only restates the mutation and target without explaining side effects, whether duplicate URLs are allowed, or how the attachment is stored/displayed.

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 a single, front-loaded sentence with no filler or redundancy. Every word earns its place in conveying the core action and target.

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

Completeness3/5

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

For a simple mutation with fully documented parameters, the description is minimally viable. However, with no annotations and no output schema, it lacks behavioral caveats and usage context such as duplicate handling or permission requirements.

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 schema already documents url, name, and cardId. The description adds no additional parameter-level meaning beyond the schema, making the baseline score appropriate.

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 states a specific action ('Add'), a specific resource ('URL attachment'), and a target ('Trello card'), fully identifying the tool's purpose. This clearly distinguishes it from sibling tools such as list_attachments, delete_attachment, and add_comment.

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?

The description provides no guidance on when to use this tool versus alternatives like list_attachments or delete_attachment. It also fails to mention any prerequisites, such as card existence or required permissions.

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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