AWS OpenSearch MCP Server

list_indices

List OpenSearch indices matching a pattern, ordered by storage size, showing health, shard count, and document count for monitoring and diagnostics.

Instructions

List matching indices ordered by storage size with health, shards and document counts.

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": "<profile>",
      "region": "<region>",
      "domain": "<domain>"
    },
    "name": "list_indices"
  }
}

Input Schema

Name	Required	Default
`domain`	Yes
`region`	Yes
`profile`	Yes
`index_pattern`	No	*

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 8, 2026

TDQS

B3.1/5.0

Behavior3/5

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

With no annotations, the description partially discloses behavior by stating the ordering and output fields. However, it omits details on pagination, result limits, or potential side effects. This is adequate but not thorough.

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 a single clear sentence, front-loaded with the action and key details. Every word serves a purpose without repetition.

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?

Given 4 parameters and no annotation support, the description lacks completeness. It does not explain the required parameters or how 'index_pattern' filters results. The output schema exists but the description only hints at output fields; still insufficient for confident use.

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

Parameters1/5

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

Schema description coverage is 0%, and the description does not explain any parameters. It only implies index_pattern through 'matching' but does not clarify the meaning of 'profile', 'region', or 'domain'. The description adds no value beyond the schema's structure.

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 tool lists indices, specifies ordering by storage size, and mentions included fields (health, shards, document counts). It distinguishes from sibling tools like 'get_index_details' which focuses on a single index.

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?

No guidance is provided on when to use this tool versus alternatives like 'get_index_details' or 'search_index'. The description does not mention prerequisite steps or exclusions.

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