search_events returns HTTP 404 while search_issues + search_issue_events succeed (mcp.sentry.dev hosted) #937

Environment

• Server: Hosted remote MCP server at https://mcp.sentry.dev/mcp
• Client: Claude Code (OAuth)
• Organization: info618 (region: us.sentry.io)
• Project: b2m-hub
• Date observed: 2026-05-07

Symptom

search_events consistently returns HTTP 404: API request failed: Not Found regardless of parameters. The other AI-agent-backed tools (search_issues, search_issue_events) work fine against the same org/project, which makes this distinct from prior outages where the embedded agent failed for all three together.

Affected tool

• ❌ search_events — HTTP 404 from Sentry REST API on every call

Working tools (verified in same session, same org)

• ✅ whoami
• ✅ find_organizations (returns info618, regionUrl https://us.sentry.io)
• ✅ find_projects (returns b2m-hub)
• ✅ search_issues — returns 17 unresolved issues with full metadata
• ✅ search_issue_events — returns full event list with stacktrace, tags, geo
• ✅ get_sentry_resource (resourceType=issue) — returns full issue + first event detail

Steps to reproduce

All four variations below return the same 404:

1. Explicit dataset + Sentry-syntax query, no project

   search_events(
     organizationSlug='info618',
     regionUrl='https://us.sentry.io',
     dataset='errors',
     query='level:error',
     statsPeriod='24h',
     limit=5
   )
   

2. Explicit dataset + project

   search_events(
     organizationSlug='info618',
     regionUrl='https://us.sentry.io',
     projectSlug='b2m-hub',
     dataset='errors',
     query='level:error',
     statsPeriod='24h',
     limit=5
   )
   

3. Natural-language query

   search_events(
     organizationSlug='info618',
     regionUrl='https://us.sentry.io',
     query='how many errors today',
     limit=5,
     includeExplanation=true
   )
   

4. No regionUrl

   search_events(
     organizationSlug='info618',
     dataset='errors',
     query='level:error',
     statsPeriod='24h',
     limit=5
   )
   

Expected

Either an aggregate count (for natural-language) or a list of error events (for explicit dataset query), as documented in the tool description.

Actual

**Input Error**

There was an HTTP 404 error with your request to the Sentry API.

API error (404): API request failed: Not Found
. Please verify the parameters are correct.

You may be able to resolve the issue by addressing the concern and trying again.

Why this is distinct from prior incidents

The fact that search_issues succeeds rules out an agent-layer outage. The 404 is coming from the downstream Sentry REST call (likely /api/0/organizations/info618/events/), suggesting the URL search_events constructs is invalid for this org while the URL search_issues constructs is valid.

Adjacent unrelated bug observed

Earlier in the same session, search_docs returned HTTP 400: Invalid request on simple queries (e.g., query='Discover events API plan tier requirement', maxResults=3). Probably worth a separate triage.

Notes

• Sentry org has 17 unresolved issues right now — plenty of error data exists for search_events to return.
• search_issue_events against B2M-HUB-4R returned 3 detailed events including stacktraces — confirming the events dataset itself is reachable for this org.
• Repro is 100% — 4 distinct call shapes, all 404.