Use when you need to design or implement MongoDB data access in Spring Boot — including document modeling, Spring Data Mongo repositories/templates, indexing, optimistic concurrency, and error handling. This should trigger for requests such as Add MongoDB in Spring Boot; Review Spring Data Mongo design; Improve error handling for Mongo writes; Model MongoDB documents for a Spring Boot service; Configure Spring Data MongoDB indexes or transactions. Part of Plinth Toolkit
SkillScore73Maintained
Automatic
◆Coding pack
Last verified 8/20/2026
What it changes
Passed 13 of 18 test cases with the skill, and 4 of 18 without it.
Without skill23%
With skill73%
Checks it passed that the model alone missed
Includes `mvn clean verify` for verification.
Includes `mvn compile` before modifying code.
Includes `mvn compile` prior to implementation.
and 7 more in the full report
11 fixed5 passed either way6 still failing0 broke
Pass-rate lift
+50 pp
Tokens
-13%
Agent turns
0%
Response time
-40%
Model gemini-3.6-flashMeasured 8/20/2026v116 of 22 cases passed with skill · 18 comparable
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 11 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 11
Prompt
In a Spring Boot MongoDB `Account` document, we want an index on `email` that only applies to documents where `active` is `true`. Show how to define this partial index on the model using Spring Data Mongo annotations, and list the build verification command.
What was checked, without and with the skill
Checked
Without skill
With skill
Uses `@Indexed` with the `partialFilter` parameter.
Passed
Passed
Includes `mvn clean verify` as the verification step.
Missed
Passed
case-18 · gemini-3.6-flash · 8/20/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md42 lines2 files
Spring Boot — MongoDB
Apply Spring Data MongoDB guidance with concrete examples for design, implementation, and error handling.
Constraints
Compile before MongoDB refactors; verify after changes.
MANDATORY: Run ./mvnw compile or mvn compile before applying any change
SAFETY: If compilation fails, stop immediately
VERIFY: Run ./mvnw clean verify or mvn clean verify after applying improvements
BEFORE APPLYING: Read the reference for detailed rules and examples
When to use this skill
Add MongoDB in Spring Boot
Review Spring Data Mongo repositories/documents
Improve duplicate key handling, retries, or optimistic locking in Mongo flows
Model MongoDB documents for a Spring Boot service
Configure Spring Data MongoDB indexes or transactions
Workflow
Read reference and assess project context
Read references/315-frameworks-spring-mongodb.md and inspect persistence setup before proposing changes.
Gather scope and decide target improvements
Identify data model, consistency, and query requirements to define safe improvements.
Apply framework-aligned changes
Implement/refactor mappings, repositories, indexes, and failure handling policies.
Run verification and report results
Execute build/tests and summarize what changed, what was verified, and follow-up actions.
Use when you need to implement acceptance tests from maintainer-authored or maintainer-sanitized Gherkin scenario facts for Spring Boot applications — including selecting scenarios tagged @acceptance, implementing happy path tests with TestRestTemplate, @SpringBootTest, Testcontainers with @ServiceConnection for DB/Kafka, and WireMock for external REST stubs. Never ingest raw .feature files. This should trigger for requests such as Review Java code for Spring Boot acceptance tests; Apply best pr