Excaliself

Add comment

add_comment

Start a comment thread on a drawing, pinned to a specific element or the top-left when no element is chosen, so every member who can see the drawing sees it immediately.

Instructions

Starts a comment thread on a drawing, pinned to an element (see read_drawing for ids) or, without one, to the top-left of the drawing. Every member who can see the drawing sees it at once.

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": {
      "id": "<id>",
      "body": "<body>"
    },
    "name": "add_comment"
  }
}

Input Schema

Name	Required	Description
`id`	Yes	A drawing id from list_drawings or search_drawings.
`body`	Yes	Plain text, up to 2000 characters. No Markdown.
`elementId`	No	Pin the thread to this element.

Schema Changelog

Changes observed during successful MCP inspections.

Addedv0.11.0Nov 10, 2026

TDQS

A3.9/5.0

Behavior4/5

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

Beyond the non-read-only, non-destructive annotations, it discloses two behaviors an agent could not infer: the default top-left placement when no element is pinned, and that the comment is immediately visible to every member who can see the drawing. It does not cover edit permissions or notification side effects, which keeps it short of a 5.

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 sentences, front-loaded with the action, then placement rules, then visibility consequence. Nothing is repeated from the schema and there is no filler.

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 small three-parameter creation tool with annotations and no output schema, the description covers placement, id sourcing, and audience visibility. The remaining gaps (body format and length are handled by the schema) are minor.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: it explains what omitting elementId does (top-left fallback) rather than just restating the schema's "Pin the thread to this element." It also points to the source of the id parameter.

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 uses a specific verb and resource ("Starts a comment thread on a drawing") and implicitly separates itself from reply_to_comment by saying it starts a thread. It is clear what it creates and where, though it never names the sibling 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 Guidelines3/5

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

It gives a concrete usage pointer ("see read_drawing for ids") and explains the two placement modes, which implies when to pass elementId. It does not say when to use this versus reply_to_comment, resolve_comment, or list_comments, so routing guidance is only implied.

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