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Lucidworks MCP (Model Context Protocol) enables agentic search using Claude Code to search your Fusion data. You configure the connection once, and Claude Code can immediately search your indexed content.
The Lucidworks MCP feature requires Fusion 5.17.0 or later. To use this feature, you will need to upgrade to Fusion 5.17.0 when it becomes available.
Claude Code can connect to Fusion using MCP

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Benefits

Lucidworks MCP server provides these advantages:
  • Self-service integration: Configure Claude Code to access Fusion data without custom API development.
  • Enterprise security: Leverages Fusion’s existing security controls, including field-level security, role-based access, and audit logging.
  • Multi-tenant architecture: Support multiple use cases with different data access patterns using query profiles and collection isolation.
  • Query pipeline integration: Claude Code benefits from your custom query pipelines, ML models, and relevance tuning.
  • Extensible tool framework: Add custom tools programmatically that automatically become available to Claude Code.

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MCP server setup

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Before you begin

Before configuring MCP access, ensure you have the following:
  • Fusion 5.17 or later deployed with the MCP Server service running
  • A Fusion app configured with indexed content
  • A query profile created for MCP access
  • An API key generated in Fusion with appropriate permissions
  • Claude Code
The MCP server runs on your Fusion infrastructure at https://FUSION_HOST:FUSION_PORT/mcp.

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Configure the MCP server

If you are using self-hosted Fusion, the MCP server is configured in your Fusion configuration file. You define search experiences that map to specific Fusion applications and query profiles.
1

Open your Fusion configuration file

Open your Fusion values.yaml configuration file.
2

Add the MCP server configuration

Add the MCP server configuration with at least one search experience, as in this example:
mcp-server:
  server:
    name: Fusion MCP Server

query-pipeline:
  searchExperiences:
    - name: "YOUR_FIRST_SEARCH_EXPERIENCE_NAME"
      description: "YOUR_FIRST_SEARCH_EXPERIENCE_DESCRIPTION"
      application-name: "YOUR_FIRST_APPLICATION_NAME"
      query-profile: "YOUR_FIRST_QUERY_PROFILE"
    - name: "YOUR_SECOND_SEARCH_EXPERIENCE_NAME"
      description: "YOUR_SECOND_SEARCH_EXPERIENCE_DESCRIPTION"
      application-name: "YOUR_SECOND_APPLICATION_NAME"
      query-profile: "YOUR_SECOND_QUERY_PROFILE"
Replace the placeholder values with your own Fusion configuration. Supported configuration parameters are listed below.
3

Redeploy Fusion

The MCP server validates the configuration at deployment and requires at least one valid search experience with all required fields populated. If no valid search experiences are configured, the service fails to start with an error message.
The following configuration parameters are supported:
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mcp-server.server.name
string
required
Display name for the MCP server. This name appears to Claude Code when it connects.
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mcp-server.tools.search-documents.description
string
Description for the search_documents tool. This parameter is optional and has a safe default that includes critical dependency information.
Only override this if you understand how the tools work together. The default description instructs Claude Code to first call list_search_experiences to obtain valid search experience names. Incorrect descriptions can break the automatic workflow.
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mcp-server.tools.list-search-experiences.description
string
Description for the list_search_experiences tool. This parameter is optional and has a safe default that includes usage examples.
Only override this if you understand how the tools work together. Modifying this incorrectly can prevent Claude Code from discovering available search experiences properly.
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mcp-server.tools.get-schema.description
string
Description for the get_schema tool. This parameter is optional and has a safe default that explains field schema retrieval.
Only override this if you understand how the tools work together. Modifying this incorrectly can prevent Claude Code from properly discovering filterable and sortable fields.
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mcp-server.tools.get-document.description
string
Description for the get_document tool. This parameter is optional and has a safe default that explains document retrieval by ID.
Only override this if you understand how the tools work together. Modifying this incorrectly can prevent Claude Code from properly retrieving individual documents.
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query-pipeline.searchExperiences
array
required
List of available search experiences. Each search experience defines how the MCP server routes queries to Fusion applications. You must configure at least one search experience.
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query-pipeline.searchExperiences.name
string
required
Display name of the search experience. Claude Code uses this name to route queries.
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query-pipeline.searchExperiences.description
string
required
Description of what this search experience contains. This helps Claude Code determine which search experience to use for a given query.
A well-crafted description helps provide a seamless experience for users. Make your descriptions as detailed as possible to enable Claude Code to quickly identify the right search experience for any prompt.
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query-pipeline.searchExperiences.application-name
string
required
Fusion application name to query.
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query-pipeline.searchExperiences.query-profile
string
required
Fusion query profile to use for queries.

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Connect Claude Code

To connect Claude Code to Fusion, you need your Fusion API key for authentication. The key is sent as an HTTP header with each request.
Claude Code provides the easiest setup with a single command.
1

Add the Lucidworks MCP server

claude mcp add --transport http fusion https://FUSION_HOST:FUSION_PORT/mcp --header "x-api-key: FUSION_API_KEY"
Replace the placeholder values with your Fusion host, port, and API key.
If you receive errors when running this command, check your Claude Code version. The --transport and --scope flags require a recent version of Claude Code.
By default, MCP servers are scoped to the current project. To make the server available globally across all projects, add --scope user. To explicitly scope it to the current project, add --scope project.
2

Verify the configuration

claude mcp list
You should see fusion listed, with the HTTP transport.

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Test the connection

After configuring Claude Code, test the connection with these example prompts. These prompts verify that the MCP server is working correctly and that Claude Code can discover and use the configured search experiences.
1

Retrieve search experiences

Test whether Claude Code can successfully retrieve the configured search experiences from Fusion.

What search experiences are available?

2

Search by name

Test whether Claude Code can identify the correct search experience by name and execute a search query.

Search the Product Catalog for wireless headphones

3

Test multi-experience routing

Test multi-experience routing, verifying that Claude Code can select the appropriate search experience based on the query context.

Find recent HR policies in Employee Resources

4

Match natural language queries

Test whether Claude Code can match natural language queries to search experience descriptions and return relevant results.

What information can I find about benefits and time off policies?

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Search with MCP

Lucidworks MCP server provides four tools that work together in a discovery-to-execution pattern. Claude Code automatically determines which tool to call based on the user’s query.

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List search experiences

The list_search_experiences tool discovers available search experiences configured in Fusion. You can use this tool in the following situations:
  • You need to see what search experiences are available.
  • You need to determine which search experience to use for a specific query.
  • You need to help users who don’t know what they can search for.
Claude Code automatically calls this tool when users ask questions like “What can I search here?” or “What do I find in Fusion?”. The tool returns a list of configured search experiences with their names and descriptions. This tool takes no parameters.

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Search documents

The search_documents tool searches for documents and returns relevant results from Fusion collections. Based on user input, it automatically selects a search experience and can optionally filter and sort results. For example, in Claude Code a user can input “Find all reports from the last six months and sort them with the newest ones first” to trigger a query that uses filters to specify the document type and date range and sort to order the results by date, newest to oldest.

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Get a document

The get_document tool fetches a specific document by its ID. This is useful when search_documents has already been called and the user inquires about a specific document returned in those results. The tool returns complete details about the document, such as its title, description, URL, similar documents (if MoreLikeThis is implemented), and highlighted fields (if highlighting is implemented).

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Get the field schema

The get_schema tool retrieves available fields within a specific search experience and returns schema information with sortable and searchable capability flags. You can use this tool in the following situations:
  • You need to discover what fields exist within a particular search experience.
  • You need to determine which fields can be used for sorting.
  • You need to determine which fields can be used for filtering.
  • You need to display field information to users with human-readable names.
Claude Code automatically calls this tool before using the sort or filters parameters when searching documents, or when users ask questions like “What fields can I sort by?” or “What can I filter by?”. The tool returns field names with their display values and capability flags. By default, the tool returns only populated fields. Set includeEmptyFields=true to retrieve the complete schema.

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How the tools work together

Claude Code uses these tools in the following order:
  1. When a user asks a question without specifying a search experience, Claude Code calls list_search_experiences to discover available options.
  2. Claude Code analyzes the search experiences and matches them to the user’s query intent.
  3. Claude Code calls search_documents with the appropriate search experience.
  4. Claude Code returns results to the user.
For example, when a user asks “Find hiking backpacks,” Claude Code automatically completes the following steps:
  1. Calls list_search_experiences and receives the following data: 
    {
  "searchExperiences": [
    {"name": "Product Catalog", "description": "Outdoor gear and sporting equipment"},
    {"name": "Support Articles", "description": "Product guides, warranties, and care instructions"}
  ]
}
  2. Identifies the “Product Catalog” search experience as the one that best matches the prompt.
  3. Calls search_documents with searchExperience: "Product Catalog" and the user’s query.
  4. Returns the product results.
This pattern allows users who know nothing about Fusion’s configuration to simply ask questions and get results without needing to understand the underlying structure.

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Example use cases

The following examples demonstrate common MCP integration patterns.
If your query pipeline is configured with highlighting or MoreLikeThis, the MCP server can include those features in its responses:
Example response
{
  "jsonrpc": "2.0",
  "id": 10,
  "result": {
    "content": [],
    "isError": false,
    "structuredContent": {
      "summary": "Found 3 documents for query: search",
      "documents": [
        {
          "id": "doc-123",
          "title": "Introduction to Search Analytics",
          "url": "https://docs.example.com/search-analytics",
          "moreLikeThis": [
            {
              "id": "doc-456",
              "title": "Query Performance Optimization"
            },
            {
              "id": "doc-789",
              "title": "Relevance Tuning Best Practices"
            },
            {
              "id": "doc-321",
              "title": "Understanding Search Metrics"
            }
          ],
          "highlighting": {
            "title_t": ["Introduction to <em>Search</em> Analytics"],
            "description_t": ["Learn how to analyze and improve your <em>search</em> performance"]
          }
        }
      ],
      "searchExperiences": [],
      "querySpellcheckSuggestions": []
    }
  }
}

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Example multi-tenant configurations

Lucidworks MCP server supports multi-tenant architectures where different users or use cases access different data subsets.
You can configure separate MCP endpoints with different query profiles:
claude mcp add --transport http fusion-employee \
    https://FUSION_HOST:FUSION_PORT/mcp \
    --header "x-api-key: employee_key"
  • The employee API key accesses a server with search experiences configured for full access to all collections.
  • The contractor API key accesses a server with search experiences limited to public documentation and shared resources.
You can support both public (unauthenticated) and authenticated access patterns:
{
  "mcpServers": {
    "fusion-public": {
      "type": "http",
      "url": "https://FUSION_HOST:FUSION_PORT/mcp",
      "headers": {
        "x-api-key": "public_readonly_key"
      }
    }
  }
}
This approach enables use cases like showroom kiosks (public read-only access with search experiences configured for public documents) and internal employee tools (authenticated with search experiences configured for full access and security trimming) using the same Fusion instance.

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Troubleshooting

This section provides solutions for common MCP configuration issues.
If you cannot connect to the MCP server, verify the following:
  1. Verify the endpoint is accessible: 
     curl -X POST https://FUSION_HOST:FUSION_PORT/mcp \
 -H "Content-Type: application/json" \
 -H "Accept: text/event-stream, application/json" \
 -H "x-api-key: api-key" \
 -i \
 -d '{
   "jsonrpc": "2.0",
   "id": 1,
   "method": "initialize",
   "params": {
     "protocolVersion": "2025-11-25",
     "capabilities": {},
     "clientInfo": {
       "name": "test-client",
       "version": "1.0.0"
     }
   }
 }'
    The protocol version in this example (2025-11-25) may differ from your installed version. See the MCP schema specification for the current version.
    If the endpoint is accessible, it returns output similar to the example below. Any other result means that the endpoint is not accessible. 
    {
 "jsonrpc": "2.0",
 "id": 1,
 "result": {
   "protocolVersion": "2024-11-05",
   "capabilities": {
     "logging": {},
     "prompts": {
       "listChanged": false
     },
     "resources": {
       "subscribe": false,
       "listChanged": true
     },
     "tools": {
       "listChanged": true
     }
   },
   "serverInfo": {
     "name": "Lucidworks MCP Server",
     "version": "1.0.0"
   }
 }
}

2. Confirm that the Fusion version is 5.17 or later:
 ```bash wrap
 curl https://FUSION_HOST:FUSION_PORT/api/admin/version
  1. Check the URL path is exactly /mcp (no trailing slash, not /api/mcp).
  2. Test with verbose logging: 
    claude mcp test fusion --verbose
  1. Regenerate the API key in Fusion Admin (the key may be expired or revoked).
  2. Verify the header format is exactly x-api-key: API_KEY (case-sensitive).
  3. Test the key directly against Fusion’s API: 
    curl -H "x-api-key: abc123" https://FUSION_HOST:FUSION_PORT/api/apps/YOUR_APP/query/YOUR_PROFILE
  1. Verify the query profile exists in the specified Fusion app.
  2. Check the profile name is an exact match (case-sensitive).
  3. Ensure the API key’s role has permission to execute queries on this profile.
The x-api-key header is required for authentication:
claude mcp add --transport http fusion https://FUSION_HOST:FUSION_PORT/mcp --header "x-api-key: API_KEY"
Run this command to verify your configuration:
claude mcp list
The response should show your MCP URL:
fusion - https://FUSION_HOST:FUSION_PORT/mcp (http)
If searches complete successfully but return no results, try these steps.
  1. Verify the Fusion app contains indexed content: 
    curl "https://FUSION_HOST:FUSION_PORT/api/apps/YOUR_APP/query/YOUR_PROFILE?q=*:*"
  2. Check that the query profile has access to the expected collections.
  3. Test the same query directly in Fusion’s Query Workbench to confirm results exist.
  4. Review security trimming rules that might filter out documents for the API key’s role.
If MCP searches are slow, try these steps.
  1. Check the query profile’s pipeline stages for expensive operations.
  2. Review the query complexity (complex filter queries can impact performance).
  3. Monitor Fusion’s query logs for slow queries.
  4. Consider optimizing ML model execution or caching strategies.
  5. Verify network latency between Claude Code and the Fusion instance.
If the Lucidworks MCP server fails to start with an error message about search experiences, follow these steps.Symptom:
ERROR - No valid search experiences configured. Server cannot start without at least one valid search experience.
Exception in thread "main" java.lang.IllegalStateException: No valid search experiences configured...
Solution:
  1. Add at least one search experience with all required fields to application.yaml: 
    mcp-server:
  server:
    name: Fusion MCP Server

query-pipeline:
  searchExperiences:
    - name: "Company Knowledge"                    # Required
      description: "Internal documentation..."    # Required
      application-name: "APP_NAME"         # Required
      query-profile: "default"                    # Required
  2. Restart the server.
  3. Verify startup logs show: Found 1 valid search experience(s): [Company Knowledge]
If list_search_experiences returns fewer search experiences than you configured, follow these steps.Solution:
  1. Check server startup logs for: INFO - Found N valid search experience(s): [names]
  2. Compare logged names with your configuration.
  3. Verify all required fields are populated (name, description, application-name, query-profile).
  4. Fix configuration and restart.
If your search query returns an error message about the search experience not being configured, verify the search experience name.Symptom:
{
  "summary": "Search experience is not configured",
  "documents": [],
  "searchExperiences": [...]
}
Solution:
  1. Call list_search_experiences to get exact names.
  2. Use the exact name (case-sensitive).
Common mistakes:
  • ❌ “engineering docs” (wrong case)
  • ✅ “Engineering Docs” (exact match)
If you receive a generic error message about being unable to process the request, verify your Fusion configuration and connectivity.Symptom:
{
  "content": [{"type": "text", "text": "Error: Unable to process request"}],
  "isError": true
}
Solution:Follow these troubleshooting steps:
  1. Verify Fusion is running and accessible.
  2. Check that application-name exists in Fusion (case-sensitive).
  3. Verify query-profile exists and is enabled in Fusion.
  4. Check authentication and network connectivity.
  5. Review MCP server logs for detailed error messages.
If your search completes successfully but returns no documents, verify your data and query configuration.Symptom:
{
  "summary": "Found 0 documents",
  "documents": [],
  "searchExperiences": []
}
Solution:Follow these troubleshooting steps:
  1. Verify documents are indexed in Fusion (check Collections in Fusion UI).
  2. Try omitting the query parameter to return all documents (defaults to *:*): 
    {
  "searchExperience": "Company Knowledge"
}
  3. Try a broader query.
  4. Test the same query directly in Fusion’s Query Workbench.
  5. Verify application-name points to the correct Fusion application.
  6. Check query profile settings for permission filters.