List all indices in an Elasticsearch cluster to inspect available data sources, optionally specifying a cluster name to target non-default clusters.
List all indices.
| Name | Required | Description | Default |
|---|---|---|---|
| cluster | No | Optional cluster name. Uses the default cluster if omitted. |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v2.1.4Input schema / additionalPropertiesAdded value: +falseInput schema / properties / cluster / descriptionAdded value: +"Optional cluster name. Uses the default cluster if omitted."v2.1.2v2.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. "List" implies a safe read, but the description says nothing about permissions, pagination, result size limits, or whether it spans all clusters. For a tool with zero annotation coverage this is a notable 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 short sentence that is front-loaded and wastes no words, but it is under-specified rather than genuinely concise. There is nothing to trim, yet nothing extra is provided either.
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?
An output schema exists, so return values need not be explained, and the lone parameter is documented. But with no annotations and no usage context, the description is only minimally complete for an agent deciding between this and its many siblings.
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%, and the single optional 'cluster' parameter is fully documented in the schema (default cluster if omitted). The description adds no parameter meaning beyond that, so the baseline of 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 clear verb+resource ("List all indices"), which distinguishes it from get_index (single index) and list_aliases (different resource). However, it offers no explicit sibling differentiation or scope detail beyond the plural noun.
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 versus get_index or search_documents, and no mention of prerequisites or contexts. The agent must infer usage entirely from the name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.