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Excalidraw · Holon

by io.github.holon-sh
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get_image

Read-only

For the board's page: read the file of an image on the board, as a data URL. Without one, the board has no such file.

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": "<board>",
      "id": "<id>"
    },
    "name": "get_image"
  }
}

Input Schema

NameRequiredDescriptionDefault
idYesThe fileId of the image's Excalidraw element.
boardYesThe board's id, as in its URL.

Output Schema

NameRequiredDescriptionDefault
dataURLNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observed

TDQS

B3.4/5.0
Behavior3/5

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

The annotations already declare readOnlyHint=true, and the description is consistent with a safe read. Beyond that it adds the return encoding (data URL) and a precondition that the file must already exist on the board, but it says nothing about size limits, failure behavior, or whether large images are truncated.

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

Conciseness4/5

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

Two short sentences with the purpose front-loaded and no redundant padding. The trailing clause 'Without one, the board has no such file' is awkwardly worded and slightly obscure, which costs it a point.

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?

An output schema exists, so return values need not be explained, and the tool is a simple two-parameter read. The description covers purpose, scope, and the existence precondition, but leaves unclear how to obtain the fileId and what happens on a missing or invalid image.

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 coverage is 100%, with both 'board' and 'id' fully documented in the schema, so baseline is 3. The description reinforces that 'id' refers to an image element on the board but adds no new syntax, format, or constraint information beyond the schema.

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 names a specific verb (read) and resource (an image file on a given board) and states the return form (data URL), so an agent knows exactly what it gets. It does not explicitly differentiate itself from the write counterpart put_image, so a 4 rather than a 5.

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?

Usage is only implied: the scoping phrase 'For the board's page' and the requirement that the file already exist signal when the tool applies. There is no explicit guidance about when to prefer put_image, read_board, or what to do if the image hasn't been uploaded yet.

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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