The Elasticsearch server has 5 well-named tools with clear descriptions and valid JSON Schema inputs. Naming follows verb_noun convention (list_indices, get_mappings, search, esql, get_shards). Descriptions are present and reasonably detailed (77-180 chars). All tools have properly typed input schemas with field descriptions. However, output schemas are not documented in the source code provided, we see only that tools return CallToolResult, but the actual response structure is not visible. Parameter descriptions are present but brief. Error handling guidance is minimal. The server uses Streamable HTTP transport and rmcp 0.2.1 with proper tool_router macro registration.

• Document the response structure for each tool. Create a markdown or JSON Schema section listing the fields returned by list_indices (e.g., 'indices: [{name: string, size_bytes: integer, doc_count: integer}]'), get_mappings (properties: {[field_name]: {type: string, ...}}), etc.
• Add format/constraint hints to parameter descriptions. E.g., for 'index_pattern', clarify: 'Supports wildcard patterns (e.g., logs-*, my_index). Exact match if no wildcards.' For 'query_body', provide a link or brief example: 'Standard Elasticsearch Query DSL: {"query": {"match": {...}}, "size": 20}'.
• Add error handling guidance to each tool description. Example: 'If the index does not exist, returns error code 404 with message. Try list_indices to discover available indices.'
• Enforce and document result limits in search and list_indices descriptions. E.g., 'Returns up to 100 indices. Use pagination (from, size) in query_body to fetch more.' or 'Results are limited to 10,000 hits for performance; use point-in-time queries for larger sets.'
• Extend tool annotations to all tools. Add idempotentHint=true to list_indices, get_mappings, get_shards (all are read-only and safe to retry). Consider adding a tool_use_confirmation annotation if any future destructive tools are added.
• Include chaining IDs in responses. If get_mappings or search results reference index names that are used by other tools, ensure those names are returned in a consistent, referenceable format.
• Add a discovery section: 'Call list_indices first to see available indices before calling search or get_mappings.' This guides multi-step agent planning.

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry