diff --git a/packages/mcp-core/src/api-client/client.ts b/packages/mcp-core/src/api-client/client.ts
index c067f5afc..6c503c45b 100644
--- a/packages/mcp-core/src/api-client/client.ts
+++ b/packages/mcp-core/src/api-client/client.ts
@@ -3259,7 +3259,7 @@ export class SentryApiService {
     opts?: RequestOptions,
   ): Promise<Event> {
     const body = await this.requestJSON(
-      `/organizations/${organizationSlug}/issues/${issueId}/events/${eventId}/`,
+      `/organizations/${encodeURIComponent(organizationSlug)}/issues/${encodeURIComponent(issueId)}/events/${encodeURIComponent(eventId)}/`,
       undefined,
       opts,
     );
diff --git a/packages/mcp-core/src/internal/tool-helpers/breadcrumbs.ts b/packages/mcp-core/src/internal/tool-helpers/breadcrumbs.ts
index 42aa71fd1..0bb7f8bdf 100644
--- a/packages/mcp-core/src/internal/tool-helpers/breadcrumbs.ts
+++ b/packages/mcp-core/src/internal/tool-helpers/breadcrumbs.ts
@@ -1,16 +1,19 @@
 import type { SentryApiService } from "../../api-client/index";
 
 /**
- * Fetches breadcrumbs from the latest event for an issue and formats them.
+ * Fetches breadcrumbs from an issue event and formats them.
+ * Defaults to the latest event when eventId is omitted.
  */
 export async function fetchAndFormatBreadcrumbs(
   apiService: SentryApiService,
   organizationSlug: string,
   issueId: string,
+  eventId: string = "latest",
 ): Promise<string> {
-  const event = await apiService.getLatestEventForIssue({
+  const event = await apiService.getEventForIssue({
     organizationSlug,
     issueId,
+    eventId,
   });
 
   const breadcrumbEntry = event.entries.find((e) => e.type === "breadcrumbs");
@@ -40,7 +43,7 @@ export function formatBreadcrumbs(
       "",
       `**Event ID**: ${eventId}`,
       "",
-      "No breadcrumbs found in the latest event for this issue.",
+      "No breadcrumbs found in this event for the issue.",
     ].join("\n");
   }
 
diff --git a/packages/mcp-core/src/schema.ts b/packages/mcp-core/src/schema.ts
index d14305b7f..f856f9483 100644
--- a/packages/mcp-core/src/schema.ts
+++ b/packages/mcp-core/src/schema.ts
@@ -237,7 +237,23 @@ export const ParamSentryGuide = z
       "Use either a platform (e.g., 'javascript', 'python') or platform/guide combination (e.g., 'javascript/nextjs', 'python/django').",
   );
 
-export const ParamEventId = z.string().trim().describe("The ID of the event.");
+export const ParamEventId = z
+  .string()
+  .trim()
+  .regex(
+    /^[0-9a-fA-F]{32}$/,
+    "Event ID must be a 32-character hexadecimal string",
+  )
+  .describe("The ID of the event. e.g. `c49541c747cb4d8aa3efb70ca5aba243`");
+
+/**
+ * Issue-scoped event selector used by tools that can target either a concrete
+ * event or the issue's latest event.
+ */
+export const ParamEventIdOrLatest = z
+  .union([z.literal("latest"), ParamEventId])
+  .default("latest")
+  .describe("The event ID for the issue, or `latest`. Defaults to `latest`.");
 
 export const ParamAttachmentId = z
   .string()
diff --git a/packages/mcp-core/src/skillDefinitions.json b/packages/mcp-core/src/skillDefinitions.json
index 1c5cc4f7f..8f4eed553 100644
--- a/packages/mcp-core/src/skillDefinitions.json
+++ b/packages/mcp-core/src/skillDefinitions.json
@@ -69,7 +69,7 @@
       },
       {
         "name": "get_event_stacktrace",
-        "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='abc123', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
+        "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
         "requiredScopes": ["event:read"]
       },
       {
@@ -79,7 +79,7 @@
       },
       {
         "name": "get_issue_breadcrumbs",
-        "description": "Get the breadcrumb trail from the latest event for a Sentry issue.\n\nUse this tool when you need to:\n- See the user and application actions leading up to an error\n- Inspect navigation, console, HTTP, and other breadcrumb events\n- Reconstruct the immediate context before an issue occurred\n\n<examples>\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123')\nget_issue_breadcrumbs(issueUrl='https://my-org.sentry.io/issues/PROJECT-123/')\n</examples>",
+        "description": "Get the breadcrumb trail from a Sentry issue event.\nDefaults to the latest event when eventId is omitted.\n\nUse this tool when you need to:\n- See the user and application actions leading up to an error\n- Inspect navigation, console, HTTP, and other breadcrumb events\n- Reconstruct the immediate context before an issue occurred\n- Compare breadcrumb trails across multiple events in the same issue\n\n<examples>\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123')\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243')\nget_issue_breadcrumbs(issueUrl='https://my-org.sentry.io/issues/PROJECT-123/')\n</examples>",
         "requiredScopes": ["event:read"]
       },
       {
@@ -214,7 +214,7 @@
       },
       {
         "name": "get_event_stacktrace",
-        "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='abc123', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
+        "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
         "requiredScopes": ["event:read"]
       },
       {
@@ -320,7 +320,7 @@
       },
       {
         "name": "get_event_stacktrace",
-        "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='abc123', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
+        "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
         "requiredScopes": ["event:read"]
       },
       {
@@ -330,7 +330,7 @@
       },
       {
         "name": "get_issue_breadcrumbs",
-        "description": "Get the breadcrumb trail from the latest event for a Sentry issue.\n\nUse this tool when you need to:\n- See the user and application actions leading up to an error\n- Inspect navigation, console, HTTP, and other breadcrumb events\n- Reconstruct the immediate context before an issue occurred\n\n<examples>\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123')\nget_issue_breadcrumbs(issueUrl='https://my-org.sentry.io/issues/PROJECT-123/')\n</examples>",
+        "description": "Get the breadcrumb trail from a Sentry issue event.\nDefaults to the latest event when eventId is omitted.\n\nUse this tool when you need to:\n- See the user and application actions leading up to an error\n- Inspect navigation, console, HTTP, and other breadcrumb events\n- Reconstruct the immediate context before an issue occurred\n- Compare breadcrumb trails across multiple events in the same issue\n\n<examples>\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123')\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243')\nget_issue_breadcrumbs(issueUrl='https://my-org.sentry.io/issues/PROJECT-123/')\n</examples>",
         "requiredScopes": ["event:read"]
       },
       {
diff --git a/packages/mcp-core/src/toolDefinitions.json b/packages/mcp-core/src/toolDefinitions.json
index 039a0ea42..2770a2d38 100644
--- a/packages/mcp-core/src/toolDefinitions.json
+++ b/packages/mcp-core/src/toolDefinitions.json
@@ -2321,7 +2321,8 @@
         },
         "eventId": {
           "type": "string",
-          "description": "The ID of the event."
+          "pattern": "^[0-9a-fA-F]{32}$",
+          "description": "The ID of the event. e.g. `c49541c747cb4d8aa3efb70ca5aba243`"
         },
         "attachmentId": {
           "default": null,
@@ -2356,7 +2357,7 @@
   },
   {
     "name": "get_event_stacktrace",
-    "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='abc123', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
+    "description": "Get a full thread stacktrace from a specific Sentry event.\n\nUse this tool when you need to:\n- Fetch the full stacktrace for a thread listed in issue details\n- Inspect a non-crashed thread from an event with multiple threads\n- Get Sentry's default selected thread stacktrace when no thread is specified\n\n<examples>\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243', thread=259)\nget_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')\n</examples>\n\n<hints>\n- `thread` is optional. If omitted, this returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.\n- Pass `thread` as a numeric Thread ID or exact thread Name from the issue details thread list.\n- If the issue details show only one useful thread, omit `thread`.\n</hints>",
     "inputSchema": {
       "type": "object",
       "properties": {
@@ -2382,8 +2383,18 @@
         },
         "eventId": {
           "default": "latest",
-          "description": "The event ID for the issue. Defaults to `latest`.",
-          "type": "string"
+          "description": "The event ID for the issue, or `latest`. Defaults to `latest`.",
+          "anyOf": [
+            {
+              "type": "string",
+              "const": "latest"
+            },
+            {
+              "type": "string",
+              "pattern": "^[0-9a-fA-F]{32}$",
+              "description": "The ID of the event. e.g. `c49541c747cb4d8aa3efb70ca5aba243`"
+            }
+          ]
         },
         "thread": {
           "description": "Optional thread selector. Pass a numeric thread ID, or an exact thread name string. If omitted, returns the same default thread Sentry selects: first crashed thread, then first thread with a stacktrace, then first thread.",
@@ -2455,7 +2466,7 @@
   },
   {
     "name": "get_issue_breadcrumbs",
-    "description": "Get the breadcrumb trail from the latest event for a Sentry issue.\n\nUse this tool when you need to:\n- See the user and application actions leading up to an error\n- Inspect navigation, console, HTTP, and other breadcrumb events\n- Reconstruct the immediate context before an issue occurred\n\n<examples>\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123')\nget_issue_breadcrumbs(issueUrl='https://my-org.sentry.io/issues/PROJECT-123/')\n</examples>",
+    "description": "Get the breadcrumb trail from a Sentry issue event.\nDefaults to the latest event when eventId is omitted.\n\nUse this tool when you need to:\n- See the user and application actions leading up to an error\n- Inspect navigation, console, HTTP, and other breadcrumb events\n- Reconstruct the immediate context before an issue occurred\n- Compare breadcrumb trails across multiple events in the same issue\n\n<examples>\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123')\nget_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243')\nget_issue_breadcrumbs(issueUrl='https://my-org.sentry.io/issues/PROJECT-123/')\n</examples>",
     "inputSchema": {
       "type": "object",
       "properties": {
@@ -2483,6 +2494,21 @@
           "type": "string",
           "format": "uri",
           "description": "The URL of the issue. e.g. https://my-organization.sentry.io/issues/PROJECT-1Z43"
+        },
+        "eventId": {
+          "default": "latest",
+          "description": "The event ID for the issue, or `latest`. Defaults to `latest`.",
+          "anyOf": [
+            {
+              "type": "string",
+              "const": "latest"
+            },
+            {
+              "type": "string",
+              "pattern": "^[0-9a-fA-F]{32}$",
+              "description": "The ID of the event. e.g. `c49541c747cb4d8aa3efb70ca5aba243`"
+            }
+          ]
         }
       }
     },
@@ -2518,7 +2544,8 @@
         },
         "eventId": {
           "type": "string",
-          "description": "The ID of the event."
+          "pattern": "^[0-9a-fA-F]{32}$",
+          "description": "The ID of the event. e.g. `c49541c747cb4d8aa3efb70ca5aba243`"
         },
         "issueUrl": {
           "type": "string",
diff --git a/packages/mcp-core/src/tools/catalog/get-event-attachment.test.ts b/packages/mcp-core/src/tools/catalog/get-event-attachment.test.ts
index 18485a467..b1b9b9ebe 100644
--- a/packages/mcp-core/src/tools/catalog/get-event-attachment.test.ts
+++ b/packages/mcp-core/src/tools/catalog/get-event-attachment.test.ts
@@ -1,4 +1,4 @@
-import { describe, it, expect } from "vitest";
+import { describe, expect, it } from "vitest";
 import getEventAttachment from "./get-event-attachment.js";
 
 describe("get_event_attachment", () => {
@@ -110,7 +110,7 @@ describe("get_event_attachment", () => {
       {
         organizationSlug: "sentry-mcp-evals",
         projectSlug: "cloudflare-mcp",
-        eventId: "octet-stream-event-id",
+        eventId: "d49541c747cb4d8aa3efb70ca5aba244",
         attachmentId: "456",
         regionUrl: null,
       },
diff --git a/packages/mcp-core/src/tools/catalog/get-event-stacktrace.ts b/packages/mcp-core/src/tools/catalog/get-event-stacktrace.ts
index 897414755..6e8f4e53e 100644
--- a/packages/mcp-core/src/tools/catalog/get-event-stacktrace.ts
+++ b/packages/mcp-core/src/tools/catalog/get-event-stacktrace.ts
@@ -6,6 +6,7 @@ import { defineTool } from "../../internal/tool-helpers/define";
 import { enhanceNotFoundError } from "../../internal/tool-helpers/enhance-error";
 import { ensureIssueWithinProjectConstraint } from "../../internal/tool-helpers/issue";
 import {
+  ParamEventIdOrLatest,
   ParamIssueShortId,
   ParamOrganizationSlug,
   ParamRegionUrl,
@@ -27,7 +28,7 @@ export default defineTool({
     "",
     "<examples>",
     "get_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123')",
-    "get_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='abc123', thread=259)",
+    "get_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243', thread=259)",
     "get_event_stacktrace(organizationSlug='my-org', issueId='PROJECT-123', thread='main')",
     "</examples>",
     "",
@@ -41,11 +42,7 @@ export default defineTool({
     organizationSlug: ParamOrganizationSlug,
     regionUrl: ParamRegionUrl.nullable().default(null),
     issueId: ParamIssueShortId,
-    eventId: z
-      .string()
-      .trim()
-      .default("latest")
-      .describe("The event ID for the issue. Defaults to `latest`."),
+    eventId: ParamEventIdOrLatest,
     thread: z
       .union([z.number().int(), z.string().trim().min(1)])
       .optional()
diff --git a/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.test.ts b/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.test.ts
index d1a3170bb..61f78842e 100644
--- a/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.test.ts
+++ b/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.test.ts
@@ -1,5 +1,5 @@
 import { eventFixture, mswServer } from "@sentry/mcp-server-mocks";
-import { http, HttpResponse } from "msw";
+import { HttpResponse, http } from "msw";
 import { afterEach, describe, expect, it } from "vitest";
 import getIssueBreadcrumbs from "./get-issue-breadcrumbs.js";
 
@@ -20,6 +20,7 @@ describe("get_issue_breadcrumbs", () => {
         organizationSlug: "sentry-mcp-evals",
         regionUrl: null,
         issueId: "CLOUDFLARE-MCP-41",
+        eventId: "latest",
       },
       context,
     );
@@ -48,6 +49,7 @@ describe("get_issue_breadcrumbs", () => {
         issueUrl:
           "https://sentry-mcp-evals.sentry.io/issues/CLOUDFLARE-MCP-41/",
         regionUrl: null,
+        eventId: "latest",
       },
       context,
     );
@@ -62,6 +64,7 @@ describe("get_issue_breadcrumbs", () => {
           organizationSlug: "sentry-mcp-evals",
           issueId: "CLOUDFLARE-MCP-41",
           regionUrl: null,
+          eventId: "latest",
         },
         {
           ...context,
@@ -96,12 +99,40 @@ describe("get_issue_breadcrumbs", () => {
         organizationSlug: "sentry-mcp-evals",
         regionUrl: null,
         issueId: "CLOUDFLARE-MCP-41",
+        eventId: "latest",
       },
       context,
     );
 
     expect(result).toContain(
-      "No breadcrumbs found in the latest event for this issue.",
+      "No breadcrumbs found in this event for the issue.",
     );
   });
+
+  it("returns breadcrumbs for an explicit event ID", async () => {
+    mswServer.use(
+      http.get(
+        "https://sentry.io/api/0/organizations/sentry-mcp-evals/issues/CLOUDFLARE-MCP-41/events/c49541c747cb4d8aa3efb70ca5aba243/",
+        () =>
+          HttpResponse.json({
+            ...eventFixture,
+            id: "c49541c747cb4d8aa3efb70ca5aba243",
+          }),
+        { once: true },
+      ),
+    );
+
+    const result = await getIssueBreadcrumbs.handler(
+      {
+        organizationSlug: "sentry-mcp-evals",
+        regionUrl: null,
+        issueId: "CLOUDFLARE-MCP-41",
+        eventId: "c49541c747cb4d8aa3efb70ca5aba243",
+      },
+      context,
+    );
+
+    expect(result).toContain("# Breadcrumbs for CLOUDFLARE-MCP-41");
+    expect(result).toContain("**Event ID**: c49541c747cb4d8aa3efb70ca5aba243");
+  });
 });
diff --git a/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.ts b/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.ts
index 8984b7379..7bc49cbee 100644
--- a/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.ts
+++ b/packages/mcp-core/src/tools/catalog/get-issue-breadcrumbs.ts
@@ -9,6 +9,7 @@ import {
   parseIssueParams,
 } from "../../internal/tool-helpers/issue";
 import {
+  ParamEventIdOrLatest,
   ParamIssueShortId,
   ParamIssueUrl,
   ParamOrganizationSlug,
@@ -21,15 +22,18 @@ export default defineTool({
   skills: ["inspect", "triage"],
   requiredScopes: ["event:read"],
   description: [
-    "Get the breadcrumb trail from the latest event for a Sentry issue.",
+    "Get the breadcrumb trail from a Sentry issue event.",
+    "Defaults to the latest event when eventId is omitted.",
     "",
     "Use this tool when you need to:",
     "- See the user and application actions leading up to an error",
     "- Inspect navigation, console, HTTP, and other breadcrumb events",
     "- Reconstruct the immediate context before an issue occurred",
+    "- Compare breadcrumb trails across multiple events in the same issue",
     "",
     "<examples>",
     "get_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123')",
+    "get_issue_breadcrumbs(organizationSlug='my-org', issueId='PROJECT-123', eventId='c49541c747cb4d8aa3efb70ca5aba243')",
     "get_issue_breadcrumbs(issueUrl='https://my-org.sentry.io/issues/PROJECT-123/')",
     "</examples>",
   ].join("\n"),
@@ -38,6 +42,7 @@ export default defineTool({
     regionUrl: ParamRegionUrl.nullable().default(null),
     issueId: ParamIssueShortId.optional(),
     issueUrl: ParamIssueUrl.optional(),
+    eventId: ParamEventIdOrLatest,
   },
   annotations: {
     readOnlyHint: true,
@@ -69,12 +74,14 @@ export default defineTool({
         apiService,
         parsed.organizationSlug,
         parsed.issueId,
+        params.eventId,
       );
     } catch (error) {
       if (error instanceof ApiNotFoundError) {
         throw enhanceNotFoundError(error, {
           organizationSlug: parsed.organizationSlug,
           issueId: parsed.issueId,
+          eventId: params.eventId,
         });
       }
       throw error;
diff --git a/packages/mcp-core/src/tools/catalog/get-issue-details.ts b/packages/mcp-core/src/tools/catalog/get-issue-details.ts
index 1060db499..d2f069de4 100644
--- a/packages/mcp-core/src/tools/catalog/get-issue-details.ts
+++ b/packages/mcp-core/src/tools/catalog/get-issue-details.ts
@@ -1,7 +1,6 @@
 import { setTag } from "@sentry/core";
-import { z } from "zod";
-import { ApiNotFoundError } from "../../api-client";
 import type { SentryApiService } from "../../api-client";
+import { ApiNotFoundError } from "../../api-client";
 import type {
   AutofixRunState,
   DefaultEvent,
@@ -27,6 +26,7 @@ import {
   parseIssueParams,
 } from "../../internal/tool-helpers/issue";
 import {
+  ParamEventId,
   ParamIssueShortId,
   ParamIssueUrl,
   ParamOrganizationSlug,
@@ -88,7 +88,7 @@ export default defineTool({
     organizationSlug: ParamOrganizationSlug.optional(),
     regionUrl: ParamRegionUrl.nullable().default(null),
     issueId: ParamIssueShortId.optional(),
-    eventId: z.string().trim().describe("The ID of the event.").optional(),
+    eventId: ParamEventId.optional(),
     issueUrl: ParamIssueUrl.optional(),
   },
   annotations: {
diff --git a/packages/mcp-server-mocks/src/index.ts b/packages/mcp-server-mocks/src/index.ts
index 64a5c5aed..1794b834c 100644
--- a/packages/mcp-server-mocks/src/index.ts
+++ b/packages/mcp-server-mocks/src/index.ts
@@ -1507,7 +1507,7 @@ export const restHandlers = buildHandlers([
   // Step 1 (metadata), so the attachment is rendered as an image not a blob.
   {
     method: "get",
-    path: "/api/0/projects/sentry-mcp-evals/cloudflare-mcp/events/octet-stream-event-id/attachments/",
+    path: "/api/0/projects/sentry-mcp-evals/cloudflare-mcp/events/d49541c747cb4d8aa3efb70ca5aba244/attachments/",
     fetch: () =>
       HttpResponse.json([
         {
@@ -1524,7 +1524,7 @@ export const restHandlers = buildHandlers([
   },
   {
     method: "get",
-    path: "/api/0/projects/sentry-mcp-evals/cloudflare-mcp/events/octet-stream-event-id/attachments/456/",
+    path: "/api/0/projects/sentry-mcp-evals/cloudflare-mcp/events/d49541c747cb4d8aa3efb70ca5aba244/attachments/456/",
     fetch: () => {
       const mockBlob = new Blob(["fake image data"], { type: "image/png" });
       return new HttpResponse(mockBlob, {