AppSignal MCP Server

Implementation Reference

• src/mcp/server.ts:114-141 (registration)

  Registration of the MCP 'getIncident' tool, including input schema validation with Zod and the handler function that calls AppSignalClient.getIncident and formats the response as text content.

  this.server.tool(
    'getIncident',
    {
      incidentNumber: z.number().int().positive(),
    },
    async ({ incidentNumber }) => {
      try {
        const incident = await this.client.getIncident(incidentNumber);
        return {
          content: [{
            type: 'text',
            text: JSON.stringify(incident, null, 2),
          }],
        };
      } catch (error) {
        if (error instanceof Error) {
          return {
            content: [{
              type: 'text',
              text: `Error fetching incident: ${error.message}`,
            }],
            isError: true,
          };
        }
        throw error;
      }
    }
  );

• src/appsignal/client.ts:103-138 (handler)

  Core handler logic in AppSignalClient that executes GraphQL query to fetch incident details from AppSignal API.

  async getIncident(incidentNumber: number): Promise<Incident> {
    const query = `
      query IncidentQuery($appId: String!, $incidentNumber: Int!) {
        app(id: $appId) {
          id
          incident(incidentNumber: $incidentNumber) {
            ... on ExceptionIncident {
              id
              number
              count
              lastOccurredAt
              actionNames
              exceptionName
              state
              namespace
              firstBacktraceLine
              errorGroupingStrategy
              severity
            }
          }
        }
      }
    `;
  
    const result = await this.executeQuery<{
      app: {
        id: string;
        incident: Incident;
      };
    }>(query, {
      appId: this.appId,
      incidentNumber,
    });
  
    return result.app.incident;
  }

• src/appsignal/client.ts:5-17 (schema)

  Zod schema defining the structure of Incident data returned by getIncident.

  export const IncidentSchema = z.object({
    id: z.string(),
    number: z.number(),
    count: z.number(),
    lastOccurredAt: z.string(),
    actionNames: z.array(z.string()),
    exceptionName: z.string(),
    state: z.string(),
    namespace: z.string(),
    firstBacktraceLine: z.string().optional(),
    errorGroupingStrategy: z.string().optional(),
    severity: z.string().optional(),
  });