excalidashapi-mcp

add_image

Inserts PNG or JPEG image bytes into a drawing at specified coordinates with optimistic version checks; no URL fetching or S3 credentials needed, and conflicts are not retried.

Instructions

Add PNG/JPEG bytes with optimistic version checking. No URL fetch or S3 credentials. Conflicts are not retried.

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": {
      "drawingId": "<drawingId>",
      "mimeType": "<mimeType>",
      "base64": "<base64>",
      "x": "<x>",
      "y": "<y>",
      "width": "<width>",
      "height": "<height>"
    },
    "name": "add_image"
  }
}

Input Schema

Name	Required	Description	Default
`x`	Yes
`y`	Yes
`width`	Yes
`base64`	Yes
`height`	Yes
`mimeType`	Yes
`drawingId`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 29, 2026

TDQS

B3.3/5.0

Behavior4/5

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

With no annotations, the description carries the full burden and does add real behavioral context: optimistic version checking, no URL/S3 fetching, and that conflicts are not retried. It omits auth requirements, return shape, and what happens on a version conflict beyond 'not retried', but the concurrency semantics are unusually well disclosed.

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?

Three tight sentences, zero filler, and the core action is front-loaded. Each sentence delivers a distinct fact (format, input mode, conflict behavior).

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 7-required-parameter mutation tool with no annotations and no output schema, the description covers concurrency and input mode but leaves coordinate/size semantics, the base64 size ceiling, and failure behavior unexplained. It is coherent but not sufficient on its own for confident invocation.

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

Parameters2/5

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

Schema description coverage is 0% across 7 required parameters, and the description explains none of them beyond implying bytes come inline rather than via URL. Nothing clarifies what x/y mean (origin, units, top-left vs center) or how width/height relate to the source image, leaving most calling decisions to guesswork.

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?

States a specific verb+resource: 'Add PNG/JPEG bytes', with the target implied by the required drawingId parameter. It is distinguishable from drawing-level siblings like create_drawing, though it never explicitly says it inserts the image into a drawing or names the sibling operation it differs from.

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?

There is no guidance on when to use this versus alternatives such as apply_drawing_ops or other element-mutating tools. The only usage-adjacent statement is a negative input constraint ('No URL fetch or S3 credentials'), which tells the agent what it cannot pass but not when to pick this tool.

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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