feat(mcp): add get_span_details tool

Returns the fully detailed span with attributes and AI enrichment data

Author: ericallam

apps/webapp/app/routes/api.v1.runs.$runId.spans.$spanId.ts

@@ -0,0 +1,132 @@
+import { json } from "@remix-run/server-runtime";
+import { BatchId } from "@trigger.dev/core/v3/isomorphic";
+import { z } from "zod";
+import { $replica } from "~/db.server";
+import { extractAISpanData } from "~/components/runs/v3/ai";
+import { createLoaderApiRoute } from "~/services/routeBuilders/apiBuilder.server";
+import { resolveEventRepositoryForStore } from "~/v3/eventRepository/index.server";
+import { getTaskEventStoreTableForRun } from "~/v3/taskEventStore.server";
+
+const ParamsSchema = z.object({
+  runId: z.string(),
+  spanId: z.string(),
+});
+
+export const loader = createLoaderApiRoute(
+  {
+    params: ParamsSchema,
+    allowJWT: true,
+    corsStrategy: "all",
+    findResource: (params, auth) => {
+      return $replica.taskRun.findFirst({
+        where: {
+          friendlyId: params.runId,
+          runtimeEnvironmentId: auth.environment.id,
+        },
+      });
+    },
+    shouldRetryNotFound: true,
+    authorization: {
+      action: "read",
+      resource: (run) => ({
+        runs: run.friendlyId,
+        tags: run.runTags,
+        batch: run.batchId ? BatchId.toFriendlyId(run.batchId) : undefined,
+        tasks: run.taskIdentifier,
+      }),
+      superScopes: ["read:runs", "read:all", "admin"],
+    },
+  },
+  async ({ params, resource: run, authentication }) => {
+    const eventRepository = resolveEventRepositoryForStore(run.taskEventStore);
+    const eventStore = getTaskEventStoreTableForRun(run);
+
+    const span = await eventRepository.getSpan(
+      eventStore,
+      authentication.environment.id,
+      params.spanId,
+      run.traceId,
+      run.createdAt,
+      run.completedAt ?? undefined
+    );
+
+    if (!span) {
+      return json({ error: "Span not found" }, { status: 404 });
+    }
+
+    const durationMs = span.duration / 1_000_000;
+
+    const aiData =
+      span.properties && typeof span.properties === "object"
+        ? extractAISpanData(span.properties as Record<string, unknown>, durationMs)
+        : undefined;
+
+    const triggeredRuns = await $replica.taskRun.findMany({
+      select: {
+        friendlyId: true,
+        taskIdentifier: true,
+        status: true,
+        createdAt: true,
+      },
+      where: {
+        parentSpanId: params.spanId,
+      },
+    });
+
+    const properties =
+      span.properties &&
+      typeof span.properties === "object" &&
+      Object.keys(span.properties as Record<string, unknown>).length > 0
+        ? (span.properties as Record<string, unknown>)
+        : undefined;
+
+    return json(
+      {
+        spanId: span.spanId,
+        parentId: span.parentId,
+        runId: run.friendlyId,
+        message: span.message,
+        isError: span.isError,
+        isPartial: span.isPartial,
+        isCancelled: span.isCancelled,
+        level: span.level,
+        startTime: span.startTime,
+        duration: span.duration,
+        durationMs,
+        properties,
+        events: span.events?.length ? span.events : undefined,
+        entityType: span.entity.type ?? undefined,
+        ai: aiData
+          ? {
+              model: aiData.model,
+              provider: aiData.provider,
+              operationName: aiData.operationName,
+              inputTokens: aiData.inputTokens,
+              outputTokens: aiData.outputTokens,
+              totalTokens: aiData.totalTokens,
+              cachedTokens: aiData.cachedTokens,
+              reasoningTokens: aiData.reasoningTokens,
+              inputCost: aiData.inputCost,
+              outputCost: aiData.outputCost,
+              totalCost: aiData.totalCost,
+              tokensPerSecond: aiData.tokensPerSecond,
+              msToFirstChunk: aiData.msToFirstChunk,
+              durationMs: aiData.durationMs,
+              finishReason: aiData.finishReason,
+              responseText: aiData.responseText,
+            }
+          : undefined,
+        triggeredRuns:
+          triggeredRuns.length > 0
+            ? triggeredRuns.map((r) => ({
+                runId: r.friendlyId,
+                taskIdentifier: r.taskIdentifier,
+                status: r.status,
+                createdAt: r.createdAt,
+              }))
+            : undefined,
+      },
+      { status: 200 }
+    );
+  }
+);

packages/cli-v3/src/mcp/config.ts

@@ -70,6 +70,12 @@ export const toolsMetadata = {
     description:
       "Get the details and trace of a run. Trace events are paginated — the first call returns run details and the first page of trace lines. Pass the returned cursor to fetch subsequent pages without re-fetching the trace. The run ID starts with run_.",
   },
+  get_span_details: {
+    name: "get_span_details",
+    title: "Get Span Details",
+    description:
+      "Get detailed information about a specific span within a run trace. Use get_run_details first to see the trace and find span IDs (shown as [spanId] in the trace output). Returns timing, properties/attributes, error info, and for AI spans: model, tokens, cost, and response data.",
+  },
   wait_for_run_to_complete: {
     name: "wait_for_run_to_complete",
     title: "Wait for Run to Complete",

packages/cli-v3/src/mcp/formatters.ts

@@ -3,6 +3,7 @@ import {
   ListRunResponseItem,
   RetrieveRunResponse,
   RetrieveRunTraceResponseBody,
+  RetrieveSpanDetailResponseBody,
 } from "@trigger.dev/core/v3/schemas";
 import type { CursorPageResponse } from "@trigger.dev/core/v3/zodfetch";
 
@@ -238,7 +239,7 @@ function formatSpan(
   const duration = formatDuration(span.data.duration);
   const startTime = formatDateTime(span.data.startTime);
 
-  lines.push(`${indent}${prefix} ${span.data.message} ${statusIndicator}`);
+  lines.push(`${indent}${prefix} [${span.id}] ${span.data.message} ${statusIndicator}`);
   lines.push(`${indent}   Duration: ${duration}`);
   lines.push(`${indent}   Started: ${startTime}`);
 
@@ -459,3 +460,94 @@ export function formatQueryResults(rows: Record<string, unknown>[]): string {
 
   return [header, separator, ...body].join("\n");
 }
+
+export function formatSpanDetail(span: RetrieveSpanDetailResponseBody): string {
+  const lines: string[] = [];
+
+  const statusIndicator = span.isCancelled
+    ? "[CANCELLED]"
+    : span.isError
+    ? "[ERROR]"
+    : span.isPartial
+    ? "[IN PROGRESS]"
+    : "[COMPLETED]";
+
+  lines.push(`## Span: ${span.message} ${statusIndicator}`);
+  lines.push(`Span ID: ${span.spanId}`);
+  if (span.parentId) lines.push(`Parent ID: ${span.parentId}`);
+  lines.push(`Run ID: ${span.runId}`);
+  lines.push(`Level: ${span.level}`);
+  lines.push(`Started: ${formatDateTime(span.startTime)}`);
+  lines.push(`Duration: ${formatDuration(span.durationMs)}`);
+  if (span.entityType) lines.push(`Entity Type: ${span.entityType}`);
+
+  if (span.ai) {
+    lines.push("");
+    lines.push("### AI Details");
+    lines.push(`Model: ${span.ai.model}`);
+    lines.push(`Provider: ${span.ai.provider}`);
+    lines.push(`Operation: ${span.ai.operationName}`);
+    lines.push(
+      `Tokens: ${span.ai.inputTokens} in / ${span.ai.outputTokens} out (${span.ai.totalTokens} total)`
+    );
+    if (span.ai.cachedTokens) {
+      lines.push(`Cached tokens: ${span.ai.cachedTokens}`);
+    }
+    if (span.ai.reasoningTokens) {
+      lines.push(`Reasoning tokens: ${span.ai.reasoningTokens}`);
+    }
+    if (span.ai.totalCost !== undefined) {
+      lines.push(`Cost: $${span.ai.totalCost.toFixed(6)}`);
+      if (span.ai.inputCost !== undefined && span.ai.outputCost !== undefined) {
+        lines.push(
+          `  Input: $${span.ai.inputCost.toFixed(6)}, Output: $${span.ai.outputCost.toFixed(6)}`
+        );
+      }
+    }
+    if (span.ai.tokensPerSecond !== undefined) {
+      lines.push(`Speed: ${span.ai.tokensPerSecond} tokens/sec`);
+    }
+    if (span.ai.msToFirstChunk !== undefined) {
+      lines.push(`Time to first chunk: ${span.ai.msToFirstChunk.toFixed(0)}ms`);
+    }
+    if (span.ai.finishReason) {
+      lines.push(`Finish reason: ${span.ai.finishReason}`);
+    }
+    if (span.ai.responseText) {
+      lines.push("");
+      lines.push("### AI Response");
+      lines.push(span.ai.responseText);
+    }
+  }
+
+  if (span.properties && Object.keys(span.properties).length > 0) {
+    lines.push("");
+    lines.push("### Properties");
+    lines.push(JSON.stringify(span.properties, null, 2));
+  }
+
+  if (span.events && span.events.length > 0) {
+    lines.push("");
+    lines.push(`### Events (${span.events.length})`);
+    const maxEvents = 10;
+    for (let i = 0; i < Math.min(span.events.length, maxEvents); i++) {
+      const event = span.events[i];
+      if (typeof event === "object" && event !== null) {
+        lines.push(JSON.stringify(event, null, 2));
+      }
+    }
+    if (span.events.length > maxEvents) {
+      lines.push(`... and ${span.events.length - maxEvents} more events`);
+    }
+  }
+
+  if (span.triggeredRuns && span.triggeredRuns.length > 0) {
+    lines.push("");
+    lines.push("### Triggered Runs");
+    for (const run of span.triggeredRuns) {
+      lines.push(`- ${run.runId} (${run.taskIdentifier}) - ${run.status.toLowerCase()}`);
+    }
+  }
+
+  return lines.join("\n");
+}

packages/cli-v3/src/mcp/schemas.ts

@@ -152,6 +152,16 @@ export const GetRunDetailsInput = CommonRunsInput.extend({
 
 export type GetRunDetailsInput = z.output<typeof GetRunDetailsInput>;
 
+export const GetSpanDetailsInput = CommonRunsInput.extend({
+  spanId: z
+    .string()
+    .describe(
+      "The span ID to get details for. You can find span IDs in the trace output from get_run_details — they appear as [spanId] before each span message."
+    ),
+});
+
+export type GetSpanDetailsInput = z.output<typeof GetSpanDetailsInput>;
+
 export const ListRunsInput = CommonProjectsInput.extend({
   cursor: z.string().describe("The cursor to use for pagination, starts with run_").optional(),
   limit: z

packages/cli-v3/src/mcp/tools.ts

@@ -15,6 +15,7 @@ import { getQuerySchemaTool, queryTool } from "./tools/query.js";
 import {
   cancelRunTool,
   getRunDetailsTool,
+  getSpanDetailsTool,
   listRunsTool,
   waitForRunToCompleteTool,
 } from "./tools/runs.js";
@@ -56,6 +57,7 @@ export function registerTools(context: McpContext) {
     triggerTaskTool,
     listRunsTool,
     getRunDetailsTool,
+    getSpanDetailsTool,
     waitForRunToCompleteTool,
     cancelRunTool,
     deployTool,

packages/cli-v3/src/mcp/tools/runs.ts

@@ -3,8 +3,8 @@ import fs from "node:fs";
 import os from "node:os";
 import path from "node:path";
 import { toolsMetadata } from "../config.js";
-import { formatRun, formatRunList, formatRunShape, formatRunTrace } from "../formatters.js";
-import { CommonRunsInput, GetRunDetailsInput, ListRunsInput, WaitForRunInput } from "../schemas.js";
+import { formatRun, formatRunList, formatRunShape, formatRunTrace, formatSpanDetail } from "../formatters.js";
+import { CommonRunsInput, GetRunDetailsInput, GetSpanDetailsInput, ListRunsInput, WaitForRunInput } from "../schemas.js";
 import { respondWithError, toolHandler } from "../utils.js";
 
 // Cache formatted traces in temp files keyed by runId.
@@ -156,6 +156,51 @@ export const getRunDetailsTool = {
   }),
 };
 
+export const getSpanDetailsTool = {
+  name: toolsMetadata.get_span_details.name,
+  title: toolsMetadata.get_span_details.title,
+  description: toolsMetadata.get_span_details.description,
+  inputSchema: GetSpanDetailsInput.shape,
+  handler: toolHandler(GetSpanDetailsInput.shape, async (input, { ctx }) => {
+    ctx.logger?.log("calling get_span_details", { input });
+
+    if (ctx.options.devOnly && input.environment !== "dev") {
+      return respondWithError(
+        `This MCP server is only available for the dev environment. You tried to access the ${input.environment} environment. Remove the --dev-only flag to access other environments.`
+      );
+    }
+
+    const projectRef = await ctx.getProjectRef({
+      projectRef: input.projectRef,
+      cwd: input.configPath,
+    });
+
+    const apiClient = await ctx.getApiClient({
+      projectRef,
+      environment: input.environment,
+      scopes: [`read:runs:${input.runId}`],
+      branch: input.branch,
+    });
+
+    const spanDetail = await apiClient.retrieveSpan(input.runId, input.spanId);
+    const formatted = formatSpanDetail(spanDetail);
+
+    const runUrl = await ctx.getDashboardUrl(
+      `/projects/v3/${projectRef}/runs/${input.runId}`
+    );
+
+    const content = [formatted];
+    if (runUrl) {
+      content.push("");
+      content.push(`[View run in dashboard](${runUrl})`);
+    }
+
+    return {
+      content: [{ type: "text", text: content.join("\n") }],
+    };
+  }),
+};
+
 export const waitForRunToCompleteTool = {
   name: toolsMetadata.wait_for_run_to_complete.name,
   title: toolsMetadata.wait_for_run_to_complete.title,

packages/core/src/v3/apiClient/index.ts

@@ -54,6 +54,7 @@ import {
   PromptOverrideCreatedResponseBody,
   RetrieveRunResponse,
   RetrieveRunTraceResponseBody,
+  RetrieveSpanDetailResponseBody,
   ScheduleObject,
   SendInputStreamResponseBody,
   StreamBatchItemsResponse,
@@ -602,6 +603,18 @@ export class ApiClient {
     );
   }
 
+  retrieveSpan(runId: string, spanId: string, requestOptions?: ZodFetchOptions) {
+    return zodfetch(
+      RetrieveSpanDetailResponseBody,
+      `${this.baseUrl}/api/v1/runs/${runId}/spans/${spanId}`,
+      {
+        method: "GET",
+        headers: this.#getHeaders(false),
+      },
+      mergeRequestOptions(this.defaultRequestOptions, requestOptions)
+    );
+  }
+
   listRuns(
     query?: ListRunsQueryParams,
     requestOptions?: ZodFetchOptions