[erikist]

Closes #100

Summary

Two bugs in how proto comments become Go string literals and JSON Schema descriptions, both in processCommentToString (cmd/protoc-gen-go-mcp/mcp.go):

1. A backslash in an RPC or message comment broke generation. processCommentToString only escaped ", so a comment like // matches \d+ produced Go source that didn't parse (strconv.Quote requires \\, not a bare \). Fixed by emitting the tool Description field with strconv.Quote(methodDescription) instead of hand-wrapping the raw string in "s.
2. Quotes were double-escaped in schema descriptions. schema.go runs comments through processCommentToString, which escaped " to \", and then json.Marshal escaped the resulting backslash a second time, so clients saw \"quote\" in tool and field descriptions. Fixed by making processCommentToString return the raw comment text, untouched beyond whitespace normalization: each caller now does its own escaping exactly once (strconv.Quote for the Go literal in mcp.go, encoding/json for the schema description in schema.go).

processCommentToString's whitespace-normalization logic (joining lines, collapsing runs of spaces) also got a small rewrite so it strips both line-comment (// foo, with per-line // prefixes) and block-comment (/* foo */) markers uniformly, without relying on the two comment styles leaving inconsistent artifacts.

Decisions made

• Added the required test characters (", \, a backtick, and a newline) to the existing example proto (examples/protos/example.proto) rather than a separate test proto, extending the SetVibeRequest.vibe field comment and the VibeService's block comment on SetVibe, since the golden-file and e2e tests already exercise that proto end to end.
• Regenerated examples/gen/example/v1/*.pb.go with make generate (protoc v29.3, protoc-gen-go v1.36.6, protoc-gen-go-grpc v1.5.1 — matching what's already pinned in golden_test.go and used elsewhere in this repo) and updated the golden file.

Test evidence

$ gofmt -l .
(no output)

$ go vet ./...
(no output)

$ go build ./...
(no output)

$ go test ./...
ok      protoc-gen-go-mcp/cmd/protoc-gen-go-mcp        0.017s
ok      protoc-gen-go-mcp/examples/gen/example/v1      (cached)
?       protoc-gen-go-mcp/cmd/mcp-vibe  [no test files]

$ go test ./cmd/protoc-gen-go-mcp -run Golden -v
--- PASS: TestGolden (0.00s)
PASS

New unit test TestProcessCommentToString (cmd/protoc-gen-go-mcp/mcp_test.go) asserts the function passes through a double quote, a backslash, a backtick, multi-line joining, and a block comment unescaped. The existing end-to-end test TestToolsList (examples/gen/example/v1/e2e_test.go) was updated to assert the SetVibe tool's description and its vibe field's schema description match the new comment text exactly, as read off the real MCP JSON-RPC wire response.

Confirmed the backslash bug existed before this fix: before the fix, adding the backslash to the proto source made go build ./... fail (invalid Go string literal) and TestToolsList showed the double-escaped quote diff.

Notes for reviewers

• Self-reviewed with the reviewer subagent against the issue's acceptance criteria; it found no blocking issues. One clarity nit about processCommentToString's internal doc comment was addressed in a follow-up commit.

• No changes outside cmd/protoc-gen-go-mcp/mcp.go, its test, the example proto, and the regenerated example files.

• Factory-authored

[erikist]

🔍 Review (Claude, on behalf of @erikist): verified in the factory image.

• Checks: make generate leaves no diff, and the golden and e2e tests pass.
• Hostile comments: I put comments containing \d+, "quoted", a backtick, */, %s %v, \\, ${x}, \u0041 and non-ASCII on an RPC, a message and two fields. The generated code compiles, and in go-sdk tools/list every description came back exactly as written.
• Escaping: backticks fall back to a quoted literal, and the double-escaping is gone.
• Normalization: multi-line comments are still joined the same way.

Nits for later:

• The doc comment at mcp.go:182-190 overstates what the trimming does: protoc already strips // and /* */.
• The new unit cases use comment shapes protoc never produces.

Merging ✅