Seq MCP Server

Instructions

Implementation Reference

• src/seq-server.ts:157-197 (handler)

  Handler function that fetches events from the Seq API endpoint '/api/events' using the provided parameters (signal, filter, count, dates, range), formats the request, and returns the JSON events or error.

  async ({ signal, filter, count, fromDateUtc, toDateUtc, range }) => {
    try {
      const params: Record<string, string> = {};
      
      // Handle date range parameters
      if (range) {
        // If range is provided, it takes precedence over fromDateUtc/toDateUtc
        params.range = range;
      } else if (fromDateUtc || toDateUtc) {
        // Only add date parameters if they're provided
        if (fromDateUtc) params.fromDateUtc = fromDateUtc;
        if (toDateUtc) params.toDateUtc = toDateUtc;
      } else {
        // Default to last hour if no time parameters provided
        params.range = '1h';
      }
  
      // Add other optional parameters
      if (signal) params.signal = signal;
      if (filter) params.filter = filter;
      if (count) params.count = count.toString();
  
      const events = await makeSeqRequest<Event[]>('/api/events', params);
      
      return {
        content: [{
          type: "text",
          text: JSON.stringify(events)
        }]
      };
    } catch (error) {
      const err = error as Error;
      return {
        content: [{
          type: "text",
          text: `Error fetching events: ${err.message}`
        }],
        isError: true
      };
    }
  }

• src/seq-server.ts:142-156 (schema)

  Input schema definition using Zod for the get-events tool parameters.

  {
    signal: z.string().optional()
      .describe('Comma-separated list of signal IDs'),
    filter: z.string().optional()
      .describe('Filter expression for events'),
    count: z.number().min(1).max(MAX_EVENTS).optional()
      .default(MAX_EVENTS)
      .describe(`Number of events to return (max ${MAX_EVENTS})`),
    fromDateUtc: z.string().optional()
      .describe('Start date/time in UTC'),
    toDateUtc: z.string().optional()
      .describe('End date/time in UTC'),
    range: timeRangeSchema.optional()
      .describe('Time range (e.g., 1m, 15m, 1h, 1d, 7d)')
  },

• src/seq-server.ts:134-198 (registration)

  Registration of the 'get-events' tool on the MCP server using server.tool() with description, input schema, and handler function.

  server.tool(
    "get-events",
    `Retrieve and analyze a list of event filtered by parameters. Use this tool when you need to:
    - Investigate events that are being logged in the SEQ server
    - Details of each event is a structured log and can provide usefull information
    - Events could be information, error, debug, or critical
    - Analyze error patterns and frequencies  
    `,
    {
      signal: z.string().optional()
        .describe('Comma-separated list of signal IDs'),
      filter: z.string().optional()
        .describe('Filter expression for events'),
      count: z.number().min(1).max(MAX_EVENTS).optional()
        .default(MAX_EVENTS)
        .describe(`Number of events to return (max ${MAX_EVENTS})`),
      fromDateUtc: z.string().optional()
        .describe('Start date/time in UTC'),
      toDateUtc: z.string().optional()
        .describe('End date/time in UTC'),
      range: timeRangeSchema.optional()
        .describe('Time range (e.g., 1m, 15m, 1h, 1d, 7d)')
    },
    async ({ signal, filter, count, fromDateUtc, toDateUtc, range }) => {
      try {
        const params: Record<string, string> = {};
        
        // Handle date range parameters
        if (range) {
          // If range is provided, it takes precedence over fromDateUtc/toDateUtc
          params.range = range;
        } else if (fromDateUtc || toDateUtc) {
          // Only add date parameters if they're provided
          if (fromDateUtc) params.fromDateUtc = fromDateUtc;
          if (toDateUtc) params.toDateUtc = toDateUtc;
        } else {
          // Default to last hour if no time parameters provided
          params.range = '1h';
        }
  
        // Add other optional parameters
        if (signal) params.signal = signal;
        if (filter) params.filter = filter;
        if (count) params.count = count.toString();
  
        const events = await makeSeqRequest<Event[]>('/api/events', params);
        
        return {
          content: [{
            type: "text",
            text: JSON.stringify(events)
          }]
        };
      } catch (error) {
        const err = error as Error;
        return {
          content: [{
            type: "text",
            text: `Error fetching events: ${err.message}`
          }],
          isError: true
        };
      }
    }
  );

• src/seq-server.ts:31-56 (helper)

  Shared helper function makeSeqRequest used by get-events tool to make authenticated HTTP requests to the Seq API.

  async function makeSeqRequest<T>(endpoint: string, params: Record<string, string> = {}): Promise<T> {
    const url = new URL(`${SEQ_BASE_URL}${endpoint}`);
    
    // Add API key as query parameter
    url.searchParams.append('apiKey', SEQ_API_KEY);
    
    // Add additional query parameters
    Object.entries(params).forEach(([key, value]) => {
      if (value !== undefined && value !== null) {
        url.searchParams.append(key, value);
      }
    });
  
    const headers: Record<string, string> = {
      'Accept': 'application/json',
      'X-Seq-ApiKey': SEQ_API_KEY
    };
  
    const response = await fetch(url.toString(), { headers });
  
    if (!response.ok) {
      throw new Error(`SEQ API error: ${response.statusText} (${response.status})`);
    }
  
    return response.json();
  }

• src/seq-server.ts:131-131 (schema)

  Zod enum schema for valid time ranges used in the get-events input schema.

  const timeRangeSchema = z.enum(['1m', '15m', '30m', '1h', '2h', '6h', '12h', '1d', '7d', '14d', '30d']);