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vishalsachdev

Canvas MCP Server

by vishalsachdev
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

Post Discussion Entry

post_discussion_entry

Posts a new top-level entry to a Canvas discussion topic, publishing it immediately as the token owner for everyone who can view the topic. Use it to reply to course discussions.

Instructions

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

Posts immediately as the token owner and is visible to everyone who can see the topic. Not idempotent: calling twice creates two entries. If create_announcement failed, do not post that content here instead: report the failure, because re-posting it publishes the message somewhere the user did not choose.

Input 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

A4.4/5.0
Behavior4/5

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

Annotations already declare idempotentHint=false and destructiveHint=false, so the bar is lower. The description adds context annotations don't carry: immediate posting, visibility to everyone who can see the topic, posting as the token owner, and the concrete consequence of duplicate calls (two entries).

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?

Four sentences, all front-loaded and purposeful. The purpose comes first, followed by behavioral notes and a specific safety warning; no sentence feels redundant.

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 mutation tool with no output schema, the description covers behavior, visibility, idempotency, and a key misuse case. It could mention what the call returns (e.g., the created entry ID), but that is a minor gap given the overall richness.

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%, so the schema already documents all three parameters. The description adds no parameter-level syntax or format details, making the baseline 3 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 states a specific verb and resource: 'Post a new top-level entry to a discussion topic.' The qualifier 'top-level' immediately distinguishes it from reply_to_discussion_entry, so an agent can select it without opening the schema.

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

Usage Guidelines5/5

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

It provides an explicit when-not: 'If create_announcement failed, do not post that content here instead.' It also implies the alternative for replies via 'top-level entry.' This is strong routing guidance for a write 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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