# Reported issues for mailchimp-mcp-server Pod holds 14 of 14 GitHub reports that passed its relevance review. This can include external user reports, maintainer-confirmed bugs, and concrete feature gaps. Treat them as evidence to inspect, not a count of distinct defects. Back to [mailchimp-mcp-server](/mcp/mailchimp-mcp-server). ## Most discussed ### bug(docker): production install crashes under QEMU ### Server version 0.3.10 ### mcp-ts-core version 0.13.9 ### Runtime Bun ### Runtime version 1.4.2 ### Transport HTTP (Streamable HTTP); failure occurs during image build ### Description The Dockerfile runs the production dependency install and [Socket scanner](https://github.com/SocketDev/bun-security-scanner) in the target architecture. On an ARM64 builder, the amd64 install crashes under QEMU even though the native compilation stage succeeds. ### Steps to reproduce On an ARM64… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/19) · 2026-09-26 · closed · 1 comment ### fix(config): pin MCP_SESSION_MODE to stateful — the image ships stateless and breaks the confirmation gate for v1 HTTP clients ### Server version 0.3.8 ### mcp-ts-core version 0.12.3 ### Runtime Bun ### Runtime version Bun 1.4.0 ### Transport HTTP (Streamable HTTP) ### Description The Docker image pins `MCP_SESSION_MODE=stateless`, preventing 2025-era HTTP clients from answering the campaign confirmation gate. `.env.example` instead documents stateful and omits `auto`. ### Steps to reproduce 1. Start the image with a valid Mailchimp API key. 2. Connect a 2025-era HTTP client supporting form elicitation. 3.… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/13) · 2026-08-22 · closed · 1 comment ### feat(discovery): surface resource URIs in playbook suggestions ### Use case The live resource catalog exposes only `mailchimp://account` through `resources/list`; the parameterized resources are discoverable via `resources/templates/list` (`mailchimp://audiences/{audienceId}`, `mailchimp://campaigns/{campaignId}`, and `mailchimp://campaigns/{campaignId}/report`) — standard MCP behavior for URI-templated resources. Many clients and agent flows do not surface resource templates prominently, and the current playbook `nextToolSuggestions` points only to… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/12) · 2026-07-02 · open · 1 comment ### bug(schema): numeric IDs rejected when MCP client sends them as strings — use z.coerce.number() on all input-side numbers ### Server version 0.2.6 ### mcp-ts-core version ^0.6.3 ### Runtime Bun ### Transport stdio ### Description Every input schema that takes a numeric ID, page count, or offset uses `z.number().int()` without `.coerce`. When an MCP client marshals those args as JSON strings (Claude Desktop, some bridges, and tool-use harnesses do this for int-shaped fields), the tool is rejected at input validation *before the handler runs*, with a message the user reads as a schema type mismatch: ``` MCP… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/3) · 2026-04-21 · closed · 1 comment ### bug: field-test round 2 — draft-report misreporting, swallowed upstream errors, UX carry-overs ### Server version 0.2.3 ### mcp-ts-core version ^0.5.0 ### Runtime Bun ### Runtime version Bun 1.3.x ### Transport stdio ### Description Second field-test pass against the live server (free-plan account, 1 audience, mix of drafts and sent campaigns). The `normalizeMailchimp()` refactor from #1 held up well and the three hard bugs from last round are gone. This pass surfaces two new bugs plus four UX findings — two of which are carry-overs from #1 that weren't in scope of that fix… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/2) · 2026-04-20 · closed · 1 comment ### bug(packaging): local asset cache enters MCPB bundles ### Server version 0.3.10 ### mcp-ts-core version 0.13.9 ### Runtime Bun ### Runtime version 1.4.2 ### Transport stdio (MCPB packaging) ### Description `bun run bundle` includes gitignored local asset-cache files. `.mcpbignore` does not exclude `.mailchimp-cache.json`, and the post-pack cleaner retains it. ### Steps to reproduce In a disposable checkout with dependencies installed: ```sh mkdir -p assets printf '%s\n' '{"version":1,"entries":{}}' > assets/.mailchimp-cache.json bun… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/18) · 2026-09-26 · open · 0 comments ### feat(mailchimp_playbook): align nextToolSuggestions entries to { toolName, reason, args } ### Use case `mailchimp_playbook` returns `nextToolSuggestions` entries as `{ tool, reason, suggestedInput? }`. Every other server that emits suggestions uses `{ toolName, reason, args }` (the shape in mcp-ts-core's `design-mcp-server` skill), so a client that executes suggestions has to special-case this one. ### Proposed behavior Rename the fields in `NextToolSchema` and in each topic branch that builds entries (`src/mcp-server/tools/definitions/mailchimp-playbook.tool.ts`), then update… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/16) · 2026-09-21 · open · 0 comments ### feat(subscribers): confirmation gate before unconsented subscribes `mailchimp_send_campaign` and `mailchimp_replicate_campaign` require `confirmSend: true` plus a re-entrant confirmation round (`ctx.requestInput` via the shared `confirmCampaignDispatch` helper) before any campaign dispatch — a real safety gate, not just a docstring warning. `mailchimp_import_subscribers` and `mailchimp_upsert_subscriber` have no equivalent: passing `status: 'subscribed'` instantly opts in up to 500 real people in one `import_subscribers` call (or one via `upsert_subscriber`),… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/14) · 2026-09-04 · open · 0 comments ## Most recent ### feat(campaigns): add a content variant selector for get-content ### Use case `mailchimp_campaigns` `operation: "get-content"` always returns whichever of `html`, `plainText`, and `archiveHtml` Mailchimp's response includes — in practice, once a campaign has HTML content, Mailchimp's content endpoint typically populates all three (with `archiveHtml` wrapping the HTML in additional archive-page/footer markup). In live testing, even a small smoke-test campaign returned overlapping bodies (`html` 2,473 chars, `plainText` 265 chars, `archiveHtml` 3,290 chars).… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/11) · 2026-07-02 · open · 0 comments ### feat(formatting): replace JSON row bullets in secondary list outputs ### Use case Several secondary/list outputs still render rows as raw JSON bullets in `content[]`. `structuredContent` is normalized, but the human/LLM text surface is low-signal and hard to scan — someone reading `content[]` (Claude Desktop-style clients, or a human) sees `- {"id":"...","url":"https://...","totalClicks":0,...}` instead of a scannable line or table. Related: #2 ### Proposed behavior Replace `JSON.stringify(row)` formatting with compact markdown tables or dimension-specific… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/10) · 2026-07-02 · open · 0 comments ### bug(subscribers): validate email inputs before hashing member IDs ### Server version 0.3.7 ### mcp-ts-core version 0.10.6 ### Runtime Bun ### Runtime version Bun 1.3.11 ### Transport HTTP (Streamable HTTP) ### OS macOS 15.x ### Description Subscriber-address inputs are plain `z.string()` fields, so malformed emails pass local validation, get MD5-hashed into a Mailchimp member ID, and come back as an upstream 404. That makes a bad local input look like a missing subscriber. ### Steps to reproduce 1. Start the server with a valid… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/9) · 2026-07-02 · open · 0 comments ### bug(mailchimp_campaigns): description advertises invalid send-checklist operation ### Server version 0.3.7 ### mcp-ts-core version 0.10.6 ### Runtime Bun ### Runtime version Bun 1.3.11 ### Transport HTTP (Streamable HTTP) ### OS macOS 15.x ### Description `mailchimp_campaigns`'s top-level tool `description` lists campaign capabilities as "...replicate, content read/write, send-checklist, and RSS/resend controls" — phrasing that reads like an enumeration of operation values, since the preceding items in the same list (`list/get/create/update`, `replicate`) *are*… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/8) · 2026-07-02 · open · 0 comments ### feat(responses): echo filters and add empty-result notice in structuredContent for list tools ### Use case List-style tools (`mailchimp_campaigns`, `mailchimp_subscribers`, `mailchimp_audiences`, and other tools with a `list`-style operation) return a bare array in `structuredContent` with no echo of the filters that produced it and no actionable notice on zero results. The empty-state guidance that exists today lives only in `format()` prose (the `content[]` text block), which API clients and Claude Code don't read — they consume `structuredContent`. An agent that gets an empty list… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/7) · 2026-05-29 · open · 0 comments ### bug: field-test follow-ups — activity-feed crash, normalization leaks, UX fixes ### Server version 0.2.1 ### mcp-ts-core version ^0.4.1 ### Runtime Bun ### Runtime version Bun 1.3.11 ### Transport stdio ### OS macOS 15.x (Darwin 25.1.0) ### Description Full field-test pass against the live server (free-plan account, 1 audience, 6 pre-existing campaigns) surfaced one hard crash, two incorrect output fields, and a set of cross-cutting UX issues around response normalization. Filing as a single rollup so the related normalization work can be scoped together. All… [Read the thread](https://github.com/cyanheads/mailchimp-mcp-server/issues/1) · 2026-04-20 · closed · 0 comments The remaining reports are on [the project's issue tracker](https://github.com/cyanheads/mailchimp-mcp-server/issues).