Upload a local file to S3-compatible storage as private, then use get_file_url to create temporary access URLs.
Save a file to S3 storage as private. Use get_file_url to get temporary access URLs.
| Name | Required | Description | Default |
|---|---|---|---|
| filePath | Yes | Path to the local file to upload | |
| filename | No | Optional custom filename for the uploaded file (defaults to original filename) | |
| description | No | Optional description/metadata for the file |
Changes observed during successful MCP inspections.
v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry behavioral disclosure. It does communicate the key trait that storage is private and that access requires a temporary URL, but says nothing about overwrite/conflict behavior, size limits, auth requirements, or failure modes.
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?
Two short sentences, zero waste, with the core action front-loaded before the related-tool pointer. Nothing could be cut without losing 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?
There is no output schema and no annotations, so the description is the only source of behavioral context for this mutation. It covers what happens (private upload) and a follow-up tool, but omits return value, error behavior, and constraints, leaving it only minimally adequate.
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 all three parameters (including the optional filename defaulting behavior) are already documented in the schema. The description adds no parameter meaning beyond that, so the baseline 3 applies.
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?
States a specific verb ('Save') plus resource ('file to S3 storage') and a distinguishing scope ('as private'), which cleanly separates it from the sibling save_public_file without needing the schema.
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?
It points to get_file_url for retrieving access URLs, which is useful follow-up routing, but gives no explicit condition for choosing this over save_public_file (the obvious alternative) and no stated prerequisites.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.