feat(mcp): add MCP-027, MCP-028, MCP-029 TypeScript and PHP parity rules

[Paramjeet-singh-neu]

Summary

• Add MCP-027: TypeScript MCP mutating tool has no idempotency key (name_has_prefix without a trailing _ + negated param_name_matches on inputSchema), matching CSDK-016 / LC-016 / MCP-007.
• Add MCP-028: Ambiguous TypeScript MCP tool name (name_in on registerTool / tool), matching MCP-003 / MCP-016 / MCP-018 / MCP-020 / MCP-022. TypeScript was the only MCP language surface with a description rule (MCP-011) but no ambiguous-name rule.
• Add MCP-029: PHP MCP mutating tool has no idempotency key (name_has_prefix with _ + negated param_name_matches on the #[McpTool] signature), matching MCP-007.

IDs MCP-023..026 were already claimed in open PRs (#80 PHP untyped, #82 stdout, #85 TS timeout, #88 description quality), so this pack starts at 027. Original Track A items that are already filed (TS HTTP timeout, PHP untyped params) are not re-filed here.

No new predicates and no schema_version bump — both matches are already used by other packs. Discovery already captures TS ParamNames from Zod inputSchema and PHP ParamNames from method signatures.

Paired PRs (same branch name feat/mcp-ts-php-parity):

• Engine fixture + tests: opened next
• Rulebook rationale: opened next

Test plan

• trustabl rules validate . on this pack
• Engine go test ./internal/rules/ -run TestPolicyRules (fire + silent cases for all three IDs)
• Confirm MCP-023..026 open PRs do not collide — this pack uses 027/028/029

Made with Cursor

[jhumel-code]

Thanks @Paramjeet-singh-neu, this is a well-researched pack. MCP-029 is a faithful PHP analog of MCP-007 (same prefix list, same negated param_name_matches, matching medium severity and 0.55 confidence), and MCP-028 reuses MCP-003's exact word list at the same low/0.85 as every other language's ambiguous-name rule, so the pack sits cleanly next to its neighbors. For MCP-027, dropping the trailing underscore so createCharge matches is the right call for TypeScript, and lowering confidence to 0.5 is an honest adjustment for the broader prefix (a read-ish name like chargeStatus would also fire). You are also correct that no predicate or schema_version change is needed, and the engine pair trustabl/trustabl#135 mirrors both files byte-identically with fire and silent cases, so the sync contract is satisfied.

One coordination note before this can land: these IDs are also claimed by other open PRs. MCP-027 and MCP-028 appear in trustabl/trustabl#168 and #91, and MCP-029 appears in trustabl/trustabl#124, trustabl/trustabl#172, #80, and #94. Whichever lands first keeps the numbers and the others will need to renumber and rebase, so expect a possible renumber here. Separately, each shipped rule needs a rationale doc in trustabl-rulebook; I saw your note that one is opened on the same branch, and we can handle or pair on that side.