jpicklyk / api-compat-review
Compatibility assessment for items with the needs-api-compat-review trait. Evaluates the MCP tool surface and the REST surface separately, since their compatibility models differ. Invoked via skillPointer when filling api-compatibility notes.
API Compatibility Review Framework
Assess API changes by surface — the MCP tool surface (dynamically re-discovered by clients) and the REST surface (hardcoded clients) have different compatibility models. Do not apply REST-style breaking-change caution to MCP tools, and do not apply MCP's rename-friendliness to REST.
Step 1: Classify the Change
Determine which surface(s) the change touches:
- MCP tools —
application/tools/tool definitions,parameterSchema, tooldescriptionstrings - REST API —
interfaces/api/v1/routes/,interfaces/api/v1/dto/Dtos.kt,openapi.yaml
A single change (e.g., a domain model field rename) can touch both surfaces independently — assess each.
Step 2: MCP Surface Assessment
LLM clients re-read the tools/list schema every session — there is no persistent client binding to break. A pure parameter rename does NOT require keeping the old name working. Verify instead:
- [ ] Every changed param's
parameterSchemakey and its arg-parsing read site stay in sync — no schema-says-X/code-reads-Y drift - [ ] ALL first-party callers update in lockstep: plugin skills, hooks (including the
orchestration-contexthook's injected text), auto-memory references, andapi-reference.md. This doc coordination is the real cost of an MCP change, not client breakage. - [ ] The tool
descriptionstring accurately reflects the new behavior
Step 3: REST Surface Assessment
HTTP clients hardcode field and param names, so compatibility DOES matter here:
- [ ] Response-shape changes are additive (new fields only) where possible
- [ ] Renames or removals of existing fields/params have an explicit migration path or version bump — not a silent break
- [ ] Note when a surface has effectively zero consumers (e.g., a days-old endpoint) so the reviewer can right-size caution instead of over-indexing on hypothetical clients
- [ ]
openapi.yamlis updated for any REST-facing change - [ ]
api-rest.mdis updated for any REST-facing change
Output
Compose the api-compatibility note with findings from Step 2 and/or Step 3, scoped to whichever surface(s) the change actually touches. If a surface wasn't touched, say so explicitly rather than omitting it silently.