openproject-mcp

Upload attachment

op_upload_attachment

Attach a local file to a work package. Optionally embed an image reference in a comment or description.

Instructions

Upload a file from the local filesystem as an attachment on a work package. Provide the absolute path to the file. Optionally override the file name. Set embedIn to "comment" or "description" to also insert an image reference () into the work package.

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": {
      "workPackageId": "<workPackageId>",
      "filePath": "<filePath>"
    },
    "name": "op_upload_attachment"
  }
}

Input Schema

Name	Required	Description
`workPackageId`	Yes
`filePath`	Yes	Absolute path to the file on disk
`fileName`	No	Override the file name (defaults to basename of filePath)
`description`	No
`embedIn`	No	Embed the uploaded file in a comment or the WP description
`embedText`	No	Text to include alongside the image reference (used with embedIn)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 26, 2026

TDQS

A3.9/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions the core action but fails to disclose important traits such as side effects (e.g., file size limits, permissions required, or return value). The description does not contradict annotations (none present), but is incomplete for a mutation tool.

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 extremely concise: two sentences covering the core purpose, key requirement (absolute path), and optional behaviors. Every sentence adds value and the most critical information is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the moderate complexity (6 parameters, no output schema), the description covers the main use case but lacks details about the return value or what happens after upload (e.g., attachment ID). It provides enough for basic usage but not full completeness.

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 description coverage is 67% (4 of 6 parameters have descriptions). The description adds value by clarifying that 'filePath' must be an absolute path, 'fileName' overrides the default, and 'embedIn' triggers insertion of an image reference. This supplements the schema's parameter descriptions well.

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 action ('upload a file'), resource ('attachment on a work package'), and key requirement ('provide the absolute path'). It distinguishes from sibling tools like op_delete_attachment and op_get_attachment by focusing on upload.

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 clear usage guidance: specify the absolute file path, optionally override the file name, and optionally embed the attachment as an image reference. It does not explicitly state when not to use or compare to alternatives, but for a single-purpose upload tool, the guidance is sufficient.

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