Add serviceOnCall tool for incident routing, bump SDK to v2026.5.12

[saditya370]

Summary

Adds a new MCP tool serviceOnCall that returns the person(s) currently on-call for a given service. Customers building incident-response agents (notably OLX) need this to route pages and operational questions to the right responder — MCP previously exposed team ownership but not the active on-call individual.

Part 2 of OpsLevel GitLab issue 14711 (gap 1 — users tool tags/teams — landed in #113).

Changes

src/cmd/root.go

• New types serializedOnCallUser and serializedOnCall — keeps the JSON output tight: {Id, Name, Email, User?}. User is populated when the on-call maps to an OpsLevel user; absent for external-only on-call records (e.g. PagerDuty users not in OpsLevel).
• New tool serviceOnCall taking a required identifier (service id or alias). Handler resolves the service, calls service.GetOnCalls(...), maps to the serialized form.
• Tool description is concise: "Returns the person currently on-call for a given service. Use this for incident-response routing."

src/go.mod / src/go.sum

• Bumped github.com/opslevel/opslevel-go/v2026 from v2026.5.6 → v2026.5.12 (release that includes the new OnCall types and Service.GetOnCalls() method).

Linked PRs

• SDK: [link to opslevel-go PR]
• Backend (GraphQL schema): [link to monolith PR — already merged + deployed]

Test plan

• go build ./... passes
• go vet ./... clean
• go tool golangci-lint run ./... clean
• Smoke test: hit the serviceOnCall tool against a real account with an on-call schedule, verify both user-mapped and external-only responders surface correctly

[andrewstillv15]

working per MCP inspector