AWS‑IReveal‑MCP

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cloudwatch_list_log_streams

List log streams in a specified AWS CloudWatch log group to monitor and analyze application logs. Retrieve structured data for troubleshooting and operational insights.

Instructions

Lists log streams in a specified CloudWatch log group.

Parameters:
  aws_region (str): The AWS region - use 'us-east-1' if not specified.
  log_group (str): The name of the log group.
  limit (int): Maximum number of log streams to return.

Returns:
  str: JSON-formatted list of log streams.

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": {
      "aws_region": "<aws_region>",
      "log_group": "<log_group>"
    },
    "name": "cloudwatch_list_log_streams"
  }
}

Input Schema

Name	Required	Description	Default
`aws_region`	Yes
`log_group`	Yes
`limit`	No

Output Schema

Name	Required	Description	Default
`result`	Yes

Implementation Reference

server.py:424-424 (registration)
The @mcp.tool() decorator registers the cloudwatch_list_log_streams function as an MCP tool.
```
@mcp.tool()
```

server.py:425-447 (handler)

The async handler function that executes the tool logic: lists log streams in the specified CloudWatch log group using boto3.logs client and returns JSON.

async def cloudwatch_list_log_streams(
    aws_region: str, 
    log_group: str, 
    limit: int = 50
) -> str:
    """
    Lists log streams in a specified CloudWatch log group.

    Parameters:
      aws_region (str): The AWS region - use 'us-east-1' if not specified.
      log_group (str): The name of the log group.
      limit (int): Maximum number of log streams to return.

    Returns:
      str: JSON-formatted list of log streams.
    """
    try:
        cw_client = boto3.client('logs', region_name=aws_region)
        response = cw_client.describe_log_streams(logGroupName=log_group, limit=limit)
        log_streams = response.get('logStreams', [])
        return json.dumps(log_streams, indent=2)
    except Exception as e:
        return f"Error listing log streams: {str(e)}"

Schema Changelog

Changes observed during successful MCP inspections.

First observedAug 15, 2025

TDQS

B3.4/5.0

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 states the action ('Lists') and return format ('JSON-formatted list'), but lacks critical behavioral details: it doesn't mention whether this is a read-only operation (though implied by 'Lists'), authentication requirements for AWS, potential rate limits, pagination behavior beyond the 'limit' parameter, error handling, or what happens if the log group doesn't exist. For a cloud service tool with zero annotation coverage, this leaves significant gaps in understanding how the tool behaves in practice.

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 efficiently structured with a clear purpose statement followed by labeled sections for 'Parameters' and 'Returns'. Each sentence earns its place by providing essential information without redundancy. The total length is appropriate for the tool's complexity, and key details are front-loaded in the opening sentence.

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 tool has 3 parameters, no annotations, and an output schema exists (implied by 'Returns: str: JSON-formatted list'), the description is moderately complete. It covers the basic purpose and parameters but lacks behavioral context like authentication, error handling, or performance considerations. The output schema handles return values, so the description doesn't need to detail them. However, for a cloud service tool with no annotations, more behavioral disclosure would improve 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?

The description adds meaningful semantics beyond the input schema, which has 0% description coverage. It explains that 'aws_region' is 'The AWS region' with a default hint ('use 'us-east-1' if not specified'), 'log_group' is 'The name of the log group', and 'limit' is 'Maximum number of log streams to return'. This clarifies the purpose of each parameter, though it doesn't provide format details (e.g., region syntax) or constraints beyond the default. With 3 parameters and low schema coverage, the description compensates well but not exhaustively.

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 ('Lists') and resource ('log streams in a specified CloudWatch log group'), making the purpose immediately understandable. It distinguishes from sibling tools like 'cloudwatch_describe_log_groups' by specifying it operates on log streams within groups rather than listing groups themselves. However, it doesn't explicitly contrast with 'cloudwatch_filter_log_events' which also involves log streams.

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

Usage Guidelines3/5

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

The description implies usage context by specifying it lists streams 'in a specified CloudWatch log group,' suggesting it should be used when you have a specific log group to examine. It doesn't provide explicit guidance on when to use this tool versus alternatives like 'cloudwatch_filter_log_events' (which filters events within streams) or mention prerequisites like needing AWS credentials. The default region hint ('use 'us-east-1' if not specified') offers some implicit guidance but not comprehensive alternatives.

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