Elastic MCP Server

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

No annotations are provided, so the description carries full burden. It mentions what statistics are returned but doesn't disclose behavioral traits like whether this is a read-only operation, performance impact, rate limits, authentication requirements, or error conditions. The description adds minimal context beyond the basic purpose.

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 is a single, efficient sentence that front-loads the purpose and key details (statistics types). Every word earns its place with zero wasted text, making it easy to parse quickly.

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 moderate complexity (statistical retrieval), no annotations, and no output schema, the description is minimally adequate. It covers what statistics are returned but lacks details on format, pagination, or error handling. For a tool with no structured safety or output information, it should provide more behavioral context.

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%, with the single parameter 'index' fully documented in the schema. The description doesn't add any parameter-specific semantics beyond what the schema provides (e.g., examples of patterns, default behavior when omitted). Baseline 3 is appropriate when the schema does the heavy lifting.

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 clearly states the verb ('Get statistics') and resource ('for one or more indices'), specifying the types of statistics (document counts, storage, and operations). It distinguishes from siblings like 'list_indices' (which lists names) and 'get_index' (which retrieves index configuration), but doesn't explicitly contrast them.

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 implies usage for retrieving statistical metrics about indices, but provides no explicit guidance on when to use this tool versus alternatives like 'cluster_stats' (cluster-level statistics) or 'nodes_stats' (node-level statistics). No exclusions or prerequisites are mentioned.

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