Discord MCP Extended

discord_fetch_image

Retrieve images from Discord CDN as base64, automatically resizing to stay within AI token limits.

Instructions

Fetch an image from Discord CDN and return it as base64. Uses iterative scaling to fit within token limits.

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": {
      "url": "<url>"
    },
    "name": "discord_fetch_image"
  }
}

Input Schema

Name	Required	Description	Default
`url`	Yes	The Discord CDN image URL (from message attachments)
`maxSizeKB`	No	Max size in KB (default 50)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.3.4Aug 9, 2026

TDQS

A3.8/5.0

Behavior3/5

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

With no annotations provided, the description carries the full transparency burden. It discloses the base64 return format and iterative scaling to fit token limits, which adds useful behavioral context. However, it does not mention error behavior, authentication needs, or non-destructive nature, leaving some gaps.

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 two sentences, front-loaded with the core purpose and immediately followed by a key behavioral detail. Every word earns its place with no redundancy.

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?

Given the simple parameter set and lack of output schema, the description sufficiently covers the tool's action, behavior, and return format. It lacks error-case details, but for a straightforward fetch operation, it is complete enough.

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%, with both 'url' and 'maxSizeKB' already explained in the schema. The description adds no additional parameter-level meaning beyond hinting at scaling via the max size parameter, so the schema does the heavy lifting.

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 uses a specific verb ('Fetch') and resource ('image from Discord CDN'), clearly stating the action and output format (base64). This distinguishes it from sibling tools, none of which handle image fetching.

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?

The description implies usage for retrieving Discord CDN images but does not explicitly state when to use it versus alternatives or provide exclusions. Siblings do not overlap functionally, so the intended context is somewhat implied but not directly guided.

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