AWS MCP Server

by Havoc24k

Overview Schema Source Related Servers Discussions Admin

Python

Hybrid

s3-list_objects_v2

List objects in an S3 bucket with filtering and pagination to manage and organize stored files efficiently.

Instructions

List objects in an S3 bucket with filtering and pagination

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": {
      "profile_name": "<profile_name>",
      "region": "<region>",
      "bucket_name": "<bucket_name>"
    },
    "name": "s3-list_objects_v2"
  }
}

Input Schema

Name	Required	Description	Default
`profile_name`	Yes
`region`	Yes
`bucket_name`	Yes
`prefix`	No
`delimiter`	No
`max_keys`	No
`continuation_token`	No
`start_after`	No
`fetch_owner`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.3Jan 26, 2026

TDQS

C2.8/5.0

Behavior2/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It mentions 'filtering and pagination' which gives some context, but fails to describe important behavioral aspects like authentication requirements (profile_name parameter), rate limits, error conditions, or what the output looks like. For a tool with 9 parameters and no annotations, this is insufficient.

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 - a single sentence that efficiently communicates the core functionality. Every word earns its place, and the structure is front-loaded with the main purpose followed by key capabilities.

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

Completeness2/5

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

For a tool with 9 parameters, no annotations, and no output schema, the description is inadequate. It doesn't explain the authentication model (profile_name), doesn't describe the return format, and provides minimal guidance on parameter usage. Given the complexity and lack of structured documentation, the description should do much more to help an agent understand how to use this tool effectively.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0% schema description coverage and 9 parameters, the description fails to compensate for the lack of parameter documentation. While 'filtering and pagination' hints at some parameters (prefix, delimiter, max_keys, continuation_token), it doesn't explain what any parameter actually does or how they interact. The description adds minimal value beyond what's already evident from parameter names.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb ('List') and resource ('objects in an S3 bucket'), making the purpose immediately understandable. It also mentions key capabilities ('with filtering and pagination'), though it doesn't explicitly differentiate from sibling tools like 's3-list_buckets' beyond the obvious resource difference.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives. While 's3-list_buckets' is clearly for listing buckets rather than objects, there's no mention of other potential alternatives or specific scenarios where this tool is appropriate versus other S3 operations.

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

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