Replace the content of an existing Slack canvas with new markdown by providing the canvas ID and updated document content.
Edit (replace content of) an existing canvas. Requires canvases:write scope.
| Name | Required | Description | Default |
|---|---|---|---|
| canvas_id | Yes | Canvas ID to edit | |
| operation_id | No | Optional idempotency key for the edit | |
| document_content | Yes | New markdown content |
Changes observed during successful MCP inspections.
v0.1.8Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It explicitly discloses that the operation replaces content, signaling destructive overwrite behavior, and it notes the authentication requirement. It does not describe return values or idempotency details, but the core behavioral trait is clearly communicated.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, front-loaded sentence that states the action, clarifies the destructive nature, and adds the required scope. There is no filler or redundant information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description is adequate for a simple mutation tool, covering purpose and auth. However, it does not mention the optional operation_id semantics, what the response will be, or when another canvas tool would be more appropriate. Given no output schema and no annotations, these gaps leave the agent with some uncertainty.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the parameters are already fully documented. The description adds no additional parameter-level meaning beyond what the schema provides. This meets the baseline for fully covered schemas.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb and resource: 'Edit (replace content of) an existing canvas.' The parenthetical clarifies that the tool overwrites content, which distinguishes it from sibling operations like create_canvas or set_canvas_access. The scope is immediately recognizable.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies use on an existing canvas and states a required OAuth scope, 'Requires canvases:write scope.' However, it does not explicitly mention when to prefer this tool over alternatives such as create_canvas or when not to use it. Usage context is present but mostly implicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.