Upload images, CSS, and other files to SharePoint Online Site Assets. Provide site ID, file name, base64 content, and optional folder path.
Upload a file (image, CSS, etc.) to Site Assets
| Name | Required | Description | Default |
|---|---|---|---|
| folder | No | Folder path (default: 'SiteAssets') | |
| siteId | Yes | ||
| fileName | Yes | File name, e.g. 'hero-banner.jpg' | |
| base64Content | Yes | Base64-encoded file content |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full behavioral burden, but it discloses only that an upload occurs. It omits overwrite behavior, file-size limits, authentication requirements, and return semantics for this mutation operation.
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?
A single sentence with the operation and destination front-loaded. There is no filler or redundancy.
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?
For a write/upload tool with no annotations, no output schema, and only minimal description, key behavioral context is missing. An agent cannot tell what happens on filename collisions, whether uploads are destructive, or what a successful response contains.
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 75%, so most parameters are already documented in the schema. The description adds file-type examples for the content but does not clarify base64 encoding expectations or folder-path behavior beyond what the schema provides, making the baseline of 3 appropriate.
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 states a specific verb (Upload), resource (file), examples of file types (image, CSS, etc.), and destination (Site Assets). It clearly separates itself from page/webpart siblings, though it does not explicitly name an alternative tool for comparison.
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?
There is no guidance on when to use this tool versus alternatives like add_image_webpart, nor any mention of prerequisites such as required permissions or valid site context. The description only restates the operation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.