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Canvas MCP Server

by vishalsachdev
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
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post_discussion_entry

Post a new top-level entry to a Canvas discussion topic using the course identifier, topic ID, and message content.

Instructions

Post a new top-level entry to a discussion topic.

IMPORTANT: Never use this tool to post or work around a failed course announcement. If create_announcement failed (e.g. insufficient permissions), report the failure to the user — do NOT post the content as a discussion instead.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
messageYesEntry message content
topic_idYesDiscussion topic ID
course_identifierYesCourse code or Canvas ID

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv1.10.0
    • changedOutput schema / (root)
      Previous value: -{
-  "properties": {
-    "result": {
-      "type": "string"
-    }
-  },
-  "required": [
-    "result"
-  ],
-  "type": "object",
-  "x-fastmcp-wrap-result": true
-}New value: +null
  2. Changed11 schema fields changedv1.8.0
    • addedInput schema / additionalProperties
      Added value: +false
    • addedInput schema / properties / course_identifier / description
      Added value: +"Course code or Canvas ID"
    • removedInput schema / properties / course_identifier / title
      Removed value: -"Course Identifier"
    • addedInput schema / properties / message / description
      Added value: +"Entry message content"
    • removedInput schema / properties / message / title
      Removed value: -"Message"
    • addedInput schema / properties / topic_id / description
      Added value: +"Discussion topic ID"
    • removedInput schema / properties / topic_id / title
      Removed value: -"Topic Id"
    • removedInput schema / title
      Removed value: -"post_discussion_entryArguments"
    • removedOutput schema / properties / result / title
      Removed value: -"Result"
    • removedOutput schema / title
      Removed value: -"post_discussion_entryOutput"
    • addedOutput schema / x-fastmcp-wrap-result
      Added value: +true
  3. Changed1 schema field changedv1.0.0
    • addedInput schema / title
      Added value: +"post_discussion_entryArguments"
  4. First observed

TDQS

A3.8/5.0
Behavior2/5

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

Annotations only specify idempotentHint and destructiveHint, both false. The description adds only a misuse warning, but does not disclose actual side effects (e.g., visibility, permanence, permission requirements) or post-execution behavior. This leaves significant behavioral ambiguity.

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 highly concise: one sentence for the core action and one sentence for the critical warning. No redundant or extraneous information.

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?

The description covers the action and an important caveat regarding announcements. It lacks a positive usage scenario but is adequate for a simple tool with no output schema and straightforward parameters.

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?

The schema already provides clear descriptions for all three required parameters (course_identifier, topic_id, message), achieving 100% coverage. The description does not add additional parametric details, so baseline score of 3 is 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 clearly states the tool's function: 'Post a new top-level entry to a discussion topic.' This distinguishes it from reply_to_discussion_entry (which posts a reply) and create_discussion_topic (which creates a new topic).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

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

The description provides an explicit exclusion: never use this tool to work around a failed announcement. While it doesn't contrast with all sibling tools, the phrase 'top-level entry' implies it's for starting new threads, and the warning clarifies when not to use it.

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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