List all files in an S3-compatible bucket with their metadata and descriptions, with optional prefix filtering to narrow results.
List all files stored in the S3 bucket with their metadata including descriptions.
| Name | Required | Description | Default |
|---|---|---|---|
| prefix | No | Optional prefix to filter files (e.g., "images/" to list only files in images folder) |
Changes observed during successful MCP inspections.
v1.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, so the description carries the full burden. It mentions listing metadata but doesn't disclose key behavioral traits like whether it's read-only (implied but not stated), pagination behavior, permission requirements, or potential rate limits. For a listing tool, this is a significant gap.
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, efficient sentence that front-loads the main action and includes relevant details about metadata. No wasted words.
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?
Given no annotations and no output schema, the description should be more complete. It covers the basic purpose but omits behavioral details like read-only nature, return format expectations, and usage context relative to siblings. Adequate but with clear gaps.
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 schema already documents the prefix parameter fully, including an example. The description doesn't add any parameter details beyond what's in the schema, so baseline 3 is 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?
States a specific verb (List) and resource (files stored in S3 bucket) with additional scope (metadata including descriptions). However, it doesn't differentiate from siblings like get_file_url or save_public_file beyond the obvious 'list' vs 'save/get' distinction, leaving room for clarity but it's fairly clear.
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?
No guidance on when to use this tool versus alternatives, such as get_file_url for specific file access. There's no mention of exclusions or prerequisites. Implied usage for listing, but lacks explicit context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.