[sentry-junior]

When a tool call leaves out organizationSlug and the login can reach exactly one organization, the call now uses that organization. When the login can reach several, a tool that requires the slug fails with a retry the model can run as is, plus the other organizations. This is the MCP version of the CLI recovery in #1634, and it finishes the part #1678 held back. The server never chooses between organizations.

Why now

Over the last 7 days (sentry/mcp-server spans, extrapolated counts):

• organizationSlug: Required failures: about 4.3K, from search_issues, find_projects, search_errors, search_logs, and calls through execute_sentry_tool. get_sentry_resource adds about 1.9K more with "organizationSlug is required when not using a URL".
• The script that sent about 89% of the earlier ~31K/week has stopped. The rest is spread out: no user accounts for more than 2 of the 40 sampled failures.

How it works

• No schema or handler edits. getFilteredInputSchema makes a required organizationSlug optional at registration time, so the MCP SDK no longer rejects the call before our code runs. Then prepareToolCallParams runs applyDefaultOrganization. Both top-level calls and execute_sentry_tool go through it, before withRoutedCredential, so stdio account routing (feat(mcp-server): Route stdio tool calls to the stored account that knows the org #1802) gets the defaulted slug.
• It runs only when the call has no slug after constraint injection and no Sentry URL parameter (it reuses getTargetOrganizationSlug). Org-scoped sessions never reach it.
• One organization: the call uses its slug. If the tool takes regionUrl and the caller didn't set one, the call also gets the organization's regionUrl. On self-hosted that value is empty, so regionUrl stays unset.
• Several organizations: for a required slug, the error looks like Retry example: `search_issues(organizationSlug='org-a', period='1h')` and lists the other organizations. Catalog tools get the execute_sentry_tool(name=…, arguments=…) form, and values equal to a schema default are left out. For an optional slug (URL-or-ID tools such as get_sentry_resource), the call runs as before.
• Listing fails (for example, a token without org:read): the error falls back to the find_organizations hint from fix(mcp): Accept 1h and minute periods; guide models to find_organizations on missing org #1678.
• Multiple logins: organizations from every account are merged.

Fit with #1669

• The organization list comes from SentryApiService.listOrganizations, which already uses the shared endpoints/organizations wrapper and transport (ref(mcp): Send Sentry API requests through the shared transport #1722, ref(mcp): Send SentryApiService requests through a shared request core #1737). No new endpoint code.
• The resolve step lives in mcp-core's constraint and param-prep layer. The design keeps that layer in mcp-core ("an MCP tool fills them from tool parameters and session constraints"), so 11.3 can keep it as is.
• The MCP hosts don't wire a CacheStore yet (7.1 is still open). Instead, the list is memoized per context and credential for 5 minutes, which matches the stable tier. When 7.1 lands, the /organizations/ request gets cached per identity on its own, and this memo can be dropped. It doesn't conflict with 8.4–8.7 or 11.x.
• This doesn't complete a task in the plan. The closest is 11.3's resolve step.

Token cost

measure-tokens is unchanged at 9,014. That script reads the raw tool schemas, and those didn't change. In the registered schemas, organizationSlug is no longer in the required list on 8 direct tools, which comes to 5,014 → 4,990 input-schema tokens.

Open questions

• A null slug still gets the find_organizations hint. Accepting null would add anyOf to every schema.
• When an optional-slug tool like get_sentry_resource is called by a user with several organizations, it keeps its own error. It doesn't list the organizations yet.

via @BYK.

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1 Skipped Deployment

Project	Deployment	Actions	Updated
sentry-local	Skipped		Nov 3, 2026 12:57am UTC

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