Elasticsearch/OpenSearch MCP Server

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. 'List all indices' implies a read-only operation, but it doesn't specify whether this requires permissions, how results are returned (e.g., pagination, format), or potential side effects. For a tool with zero annotation coverage, this leaves significant gaps in understanding its behavior.

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?

The description 'List all indices' is extremely concise—just three words—and front-loaded with the core action. There's no wasted language or unnecessary elaboration, making it efficient and easy to parse.

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 the tool's simplicity (0 parameters, no output schema), the description is minimally adequate. It states what the tool does but lacks details on behavior, usage context, or output format. With no annotations and no output schema, it should ideally provide more context about what 'list' entails (e.g., returns an array of index names), but it's sufficient for a basic listing function.

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?

The tool has 0 parameters, and schema description coverage is 100%, so there are no parameters to document. The description doesn't need to add parameter semantics, and it appropriately doesn't mention any. A baseline of 4 is justified since no parameters exist, and the schema fully covers this.

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?

The description 'List all indices' clearly states the verb ('List') and resource ('indices'), making the purpose immediately understandable. However, it doesn't differentiate from sibling tools like 'get_index' (which retrieves a specific index) or 'list_aliases' (which lists aliases rather than indices), so it doesn't fully distinguish from alternatives.

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?

The description provides no guidance on when to use this tool versus alternatives. It doesn't mention that this is for retrieving all indices at once (unlike 'get_index' for a single index) or compare it to other listing tools like 'list_aliases'. There's no context about prerequisites, timing, or exclusions.

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