Postiz API + MCP by Postiz (Gitroom)

# Fix list: Postiz API + MCP

From Anchor Terminal's listing at https://www.anchorterminal.com/tools/postiz, the October 2026 research run, assessed 1 October 2026. Grade C, 59.5 out of 100.

This is everything the published grade says the listing lacks, the biggest possible gain to the total first. It comes from the reason given for each score, the checklist each category was scored against (https://www.anchorterminal.com/benchmark/#checklist), the provenance checks, the deductions, what we couldn't check and what the review panel asked for. A fix counts at the next check, once it's public.

For a coding agent working on Postiz API + MCP: work through the items below in the product, its docs and its public pages. Each category gives the reason for its score, with the points each checklist item earned, and the checklist itself, so the gap is the items that earned less than their points. Change the product, not the wording, and keep a note of what you changed and where it's published.

## 1. Reliability, 53 out of 100, up to 9.4 more on the total

Why it scored 53: Scored for Postiz Cloud, since self-hosted uptime is the operator's. status.postiz.com is Gitroom's own page and read All Systems Operational, but showed our reader no components (15). Its history page loaded with no incidents listed, and robots.txt blocked the incident API, so we can't tell a clean record from a page our reader didn't render. Partial credit (10). 90 create-post requests an hour on every Cloud plan, matching the throttler default in source (15). The docs don't mention Retry-After, the spec documents a 429 only for clipping, and there's no idempotency key (3). No SLA found (0). The public API isn't labelled beta (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-reliability):

Hosted APIs, MCP servers, models and platforms.

- 20, a public status page with component history (Statuspage, Instatus, BetterStack or the vendor's own).
- 0 to 30, the incident record for the last 90 days on that page. 30 for a clean record or trivial incidents only, 20 for minor incidents only, 10 for one major outage (an hour or more of a core API down, or errors across the board), 0 for several. 5 when there's no history we could read, and the note says so.
- 15, rate limits documented with numbers.
- 15, documented 429 or overload handling (Retry-After, backoff guidance), and idempotency keys or safe-retry guidance where writes are involved.
- 10, an SLA published for any paid tier.
- 10, the surface agents use is generally available, not beta or preview.

Local packages, SDKs, frameworks and stdio MCP servers.

- 20, installs from an official package with supported runtimes stated.
- 25, a public CI and test suite, passing on the default branch.
- 0 to 25, open crash or regression issues relative to activity (25 for few and handled, 0 for many, old and unanswered).
- 15, semver discipline and breaking changes called out in a changelog.
- 15, version 1.0 or later, or declared stable.

Protocols are read from their reference implementations, the public facilitators or servers, spec stability and test vectors.

## 2. Security & auth, 49 out of 100, up to 8.9 more on the total

Why it scored 49: One organisation API key, sent raw in the Authorization header and rotatable from settings. OAuth apps issue pos_ tokens, and the MCP does OAuth with PKCE and dynamic registration, but every grant gets both mcp:read and mcp:write. The docs also document the key in the URL path at /mcp/{key}, so less 10 (15). No read-only key or scope. Tool annotations mark schedulePostTool destructive, and posts can go in as drafts (8). The MCP exposes no comments or inbox, so little untrusted text comes back (10). No audit log found, only notifications (2). SECURITY.md routes reports through GAdvisory with 72-hour acknowledgement and 90-day remediation targets, CVE-2026-94455 and CVE-2026-94456 were fixed on 22 September 2026, and CI runs CodeQL. No bug bounty, certification or security.txt (14).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-security):

- 0 to 30, the credential model. 30 for OAuth 2.1 with scopes, or scoped and revocable keys with rotation. 20 for plain revocable API keys. 10 for one all-powerful key. 10 off when a secret can travel in a URL query string as a documented option.
- 0 to 20, read-only or least-privilege modes, and confirmation or approval for destructive actions.
- 0 to 15, prompt-injection posture where the tool returns untrusted content (documented mitigations or guidance). A tool that returns no untrusted content gets 10.
- 0 to 15, audit logs or per-call visibility for the operator.
- 0 to 20, a security programme. security.txt or a disclosure policy, a bug bounty, SOC 2 or ISO 27001, advisories handled in public.

Models are read for retention, whether API data trains models (and whether that's off by default), zero-retention options and certifications. Frameworks for telemetry defaults, approval hooks, guardrails and sandboxing.

## 3. Payments & pricing, 30 out of 100, up to 8.8 more on the total

Why it scored 30: No x402 or other machine payment (0). Cloud plan prices are public, with no per-call price (10). Self-hosting under AGPL-3.0 is free and includes the API and MCP, with no card. The Cloud trial's card policy isn't stated (20). Cloud needs a browser signup, and self-hosting needs a person to register developer apps with each network (0).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-payments):

The published rubric, also on the [x402 page](https://www.anchorterminal.com/x402/).

- 40, a machine payment protocol (x402, MPP or L402) on the tool's own endpoints. 10 to 30 when it covers only some endpoints or only goes through a third party, and the note says which.
- 20, per-call or per-unit pricing published without a login. 10 for public plan-only pricing, 0 for "contact sales" or prices behind a login.
- 20, a free tier or trial that doesn't need a card.
- 20, autonomous onboarding, meaning an agent can get access without a person signing up in a browser (keyless use, x402, a programmatic key API).

Payment platforms and agent wallets rarely charge for their own API over a machine protocol, so the first line has steps for them, and the highest one that applies counts. 40 when x402, MPP or L402 runs on all their own endpoints, 30 when it runs on part of their own API, 25 when their merchants can accept one, 20 for running a facilitator, 15 for paying as a buyer, and 0 when the only protocol is their own. Merchant acceptance sits above a facilitator because the platform's own customers can charge agents through it, while a facilitator settles for sellers who wire up the protocol themselves. The counter-argument (a facilitator does more for the protocol as a whole) has a point. Each note says which step applied.

Open-source software you run yourself is scored on its hosted or paid option if it has one. A free, self-hosted package with nothing to buy gets 20, 20 and 20 for the last three lines, and 0 to 40 for the first only if it ships a payment protocol.

## 4. Agent ergonomics, 65 out of 100, up to 5.7 more on the total

Why it scored 65: The docs say 13 MCP tools. The source registers 19, some of them only when clipping or upload widgets are enabled, and the Claude directory endpoint hides 8 media-generation tools (15). Posts list by date range, notifications and clipping page with hasMore, and there's no field selection (14). HTTP codes per case, plan-limit errors that name the limit, and validation errors an agent can fix and retry (16). Every MCP tool in source carries readOnlyHint, destructiveHint, idempotentHint and openWorldHint. No idempotency key on REST (12). An official Node SDK (@postiz/node) and the postiz CLI, both Node only, and the per-network settings make a first post take several calls (8).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-ergonomics):

- 0 to 25, context cost. For MCP, the number and size of the tool definitions (25 for ten or fewer compact tools, 15 for 11 to 30, 5 for more than 30, plus up to 10 back for toolsets, dynamic loading or read-only subsets). For APIs, whether responses can be sized (field selection, limits, summaries).
- 20, pagination, filtering and output-size controls.
- 20, actionable, documented error responses, codes and messages an agent can recover from.
- 20, idempotency or safe retries, and for MCP the `readOnlyHint` and `destructiveHint` annotations.
- 15, sensible defaults, few required parameters, and official SDKs in at least two languages.

Models are read for tool use, structured output, prompt caching, context length, batch and SDKs. Frameworks for how much code and how many defaults a tool-calling agent with MCP needs.

## 5. Schema & documentation, 88 out of 100, up to 2 more on the total

Why it scored 88: OpenAPI 3.1.0 at docs.postiz.com/public-api/openapi.json with 27 paths, and zod input schemas on every MCP tool in source (25). llms.txt and Markdown versions of the docs pages (10). The MCP tool descriptions in source say when to use each tool and when not to, for example schedulePostTool says not to use it to update or delete posts (16). Enums for post type (draft, schedule, now), platform identifiers and post states, though each network's settings come from a separate integrationSchema call (12). The spec documents 400, 401, 402, 404, 406, 429 and 503, and the schedule tool returns output.errors naming what to fix (12). Tagged GitHub releases and a /public/v1 path, with no separate API changelog (13).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-schema):

APIs and MCP servers.

- 25, a machine-readable contract (a public OpenAPI file or similar; for MCP, typed JSON Schema inputs on every tool).
- 10, llms.txt or Markdown docs served for agents.
- 0 to 20, descriptions that say what a tool is for, when to use it and when not to, read from the tool definitions in the source or the API reference.
- 0 to 15, typed inputs with enums, constraints and required fields, and no free-form JSON blobs.
- 0 to 15, examples and documented error responses.
- 15, versioning and a public changelog.

Models are read from the API reference, the OpenAPI file, llms.txt, the structured-output and tool-use docs and the model cards. Frameworks from docs a model can follow, typed interfaces, examples and the API reference.

## 6. Transparency & trust, 83 out of 100, up to 1.5 more on the total

Made of editorial 75, provenance 90.

Why it scored 83: AGPL-3.0 (30). The privacy policy dated 3 May 2026 keeps account data up to 90 days after closure, deletes OAuth tokens on revoke and keeps billing records about 7 years. A DPA with SCCs is signed on request and AI providers are told not to train on inputs. It names Stripe, Paddle, Anthropic and OpenAI and no full list (22). The terms promise reasonable notice of material changes and 30 days for price rises, and only the latest release is supported. No API deprecation policy (8). Hosted data regions given as the US, EU, UK and others. Self-hosted Sentry reporting runs only when a DSN is set, and the compose file ships it commented out (15).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-transparency):

- 0 to 30, source availability and licence clarity. 30 for open source under an OSI licence, 15 for closed with clear terms, 0 for unclear terms.
- 0 to 30, data handling and retention statements that agree with each other (privacy policy, DPA, retention periods, subprocessors).
- 0 to 20, a deprecation policy or notices with dates.
- 0 to 20, telemetry disclosed with an opt-out (local software), or subprocessors and data locations disclosed (hosted).

The other half of Transparency and trust is the provenance score, computed from checked facts (below). The category score is the mean of the two.

Provenance checks not met in full (half of this category, computed from checked facts):

- security.txt: not found (0 of 10)

## 7. Maintenance & community, 85 out of 100, up to 1.3 more on the total

Why it scored 85: v2.24.0 on 22 September 2026, and the default branch had commits on 1 October (30). v2.22.1, v2.23.0 and v2.24.0 since July, and 502 commits since 3 July from three main maintainers (20). 121 merges on 18 days since 1 September, and 1,191 pull requests opened to date. robots.txt blocked our reader from the issue tracker, and a stale workflow closes inactive issues (15). Official Node SDK and CLI. No official MCP registry entry (10). Build, CodeQL and Dependabot on GitHub (10).

The checklist (https://www.anchorterminal.com/benchmark/#checklist-maintenance):

- 0 to 30, time since the last release, or the last published model or API change for a closed service. 30 within 30 days, 20 within 90, 10 within 180, 0 older.
- 20, at least three releases or dated changelog entries in the last 90 days.
- 0 to 25, responsiveness. Issues and pull requests answered on GitHub (the open issues and how recent the replies are). For closed services, a public changelog and a support or community channel that answers, 0 to 15.
- 15, presence in the official MCP registry under a verified namespace (MCP servers), or current official SDKs (APIs and models).
- 10, package health, current dependencies and CI.

Models are read for deprecation notice periods and model churn rather than release counts.

## Deductions

Each comes off the total. A fixed and documented problem counts for less at the next check.

- 2026-07-20 and 2026-09-22. Three security fixes in the last 12 months. A path traversal in the self-hosted upload route that could read files outside UPLOAD_DIRECTORY, fixed in commit 7936062 labelled critical, and CVE-2026-94455 (enterprise endpoints accepting other JWT types) and CVE-2026-94456 (non-cryptographic IDs for OAuth secrets and codes), fixed on 22 September. All fixed and the latter two given CVEs, so we deduct less. -3 (https://github.com/gitroomhq/postiz-app/commit/793606226f981706cc0201c8023f0f2b57ce08e4, https://github.com/gitroomhq/postiz-app/commit/9259cf2429e8cc0c88414e88d5e6c783d7ffba63)

## What we couldn't check

What we couldn't read counted as absent. Publishing it on a page a plain HTTP fetch can read (not only in a browser) lets the next check count it.

- Whether status.postiz.com's empty history is a clean record or a page our reader couldn't render
- Which of the 19 MCP tools in source are live on mcp.postiz.com. The docs say 13
- Whether the Cloud trial needs a card
- unchecked: open issues and reply times, since robots.txt blocked the GitHub issues page
- Whether advisories for the 20 July path traversal and the two September CVEs were published on GAdvisory or GitHub

## Weaknesses

- Create-post capped at 90 requests an hour on every Cloud plan
- One organisation key with no scopes, and the MCP OAuth grant is always read and write
- The docs document the API key in the MCP URL path at /mcp/{key}
- No idempotency key and no Retry-After guidance
- Self-hosting means your own developer app and review with each network

## What costs an agent a turn today

The notes we give agents before they call it. Each one is a workaround an agent shouldn't need.

- Send the key as the `Authorization` header with no `Bearer` prefix on REST calls
- Batch several posts into one create request to stay under 90 an hour
- Call integrationSchema (Get Settings) for a channel before scheduling, since each network has its own settings
- Use the Bearer header on /mcp rather than /mcp/{key} so the key stays out of logs
- Read output.errors on a failed schedule call and retry with the corrected fields

## What the review panel asked for

- Retry-After on 429
- Drop the /mcp/{key} form
- read-only OAuth scope
- drop the /mcp/{key} route

## When it's done

Send what changed and where it's published as a dispute (https://www.anchorterminal.com/builders/#disputes, or `POST https://www.anchorterminal.com/api/v1/contact` with `"kind": "dispute"`). Disputes are answered in public, and the listing is checked again by the same checklist. Paying for an audit or a listing claim changes nothing here.