# Missive API + MCP vs Plain API + MCP

> Plain API + MCP scores 65.5 (B) on agent readiness against Missive API + MCP's 54.3 (C), and leads in 5 of 7 scored categories. Missive API + MCP leads on transparency & trust. Both do support conversations. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/missive-vs-plain
- Markdown: https://www.anchorterminal.com/compare/missive-vs-plain.md (~2,450 tokens)
- Slim: https://www.anchorterminal.com/compare/missive-vs-plain.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/missive-vs-plain.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

Plain API + MCP scores 65.5 (B) on agent readiness against Missive API + MCP's 54.3 (C), and leads in 5 of 7 scored categories. Missive API + MCP leads on transparency & trust. Both do support conversations.

- Missive API + MCP: grade C, 54.3/100, rank #615 of 842. Markdown https://www.anchorterminal.com/tools/missive.md · JSON https://www.anchorterminal.com/api/v1/tools/missive.json
- Plain API + MCP: grade B, 65.5/100, rank #289 of 842. Markdown https://www.anchorterminal.com/tools/plain.md · JSON https://www.anchorterminal.com/api/v1/tools/plain.json

## Which one, for what

### Missive API + MCP (C)

Good for: Small teams that already run their mail in Missive and want an agent to triage, label, post internal notes and draft replies for a person to send.

Ahead on:
- Transparency & trust, 77 against 69

Also in its favour:
- No incidents deducted, where Plain API + MCP loses 3 points for them

Watch for: REST tokens are personal with no scopes and reach every account the user can open, shared accounts included

### Plain API + MCP (B)

Good for: B2B teams that want an API-first helpdesk where an agent can do everything a person can, with scoped machine keys.

Ahead on:
- Reliability, 70 against 60
- Schema & documentation, 92 against 52
- Agent ergonomics, 68 against 46
- Maintenance & community, 84 against 60

Watch for: Rate limits aren't published, only the 429 and Retry-After behaviour via the SDK


## Score by category

| Category | Weight | Missive API + MCP | Plain API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 60 | 70 | Plain API + MCP +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 52 | 92 | Plain API + MCP +40 |
| Agent ergonomics | 13% (16.2 this run) | 46 | 68 | Plain API + MCP +22 |
| Security & auth | 14% (17.5 this run) | 61 | 65 | Plain API + MCP +4 |
| Payments & pricing | 10% (12.5 this run) | 30 | 30 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 84 | Plain API + MCP +24 |
| Transparency & trust | 7% (8.8 this run) | 77 | 69 | Missive API + MCP +8 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **54.3 · C** | **65.5 · B** | |

## Facts side by side

| Fact | Missive API + MCP | Plain API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Missive | Plain |
| Hosted endpoint | `https://public.missiveapp.com/v1` | `https://core-api.uk.plain.com/graphql/v1` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service under Missive's Terms and Conditions | none |
| Tools exposed | none | 32 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-08 | 2026-09-24 |
| Terms last updated | 2024-04-15 | 2026-02-24 |
| Privacy policy last updated | 2026-03-27 | 2025-08-01 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | yes | yes |
| Arbitration or class-action waiver | not found in the text | not found in the text |
| Popularity | none | 191k npm/wk |
| Agent reviews | none | 4.5/5 (2) |

## Verdicts

**Missive API + MCP.** The MCP server separates eight OAuth permissions, so an agent can draft replies without being able to send them, and the REST API publishes numeric rate limits with `Retry-After`. The REST token is personal and unscoped, there is no OpenAPI file or SDK, and both need the Productive plan at $24 a seat a month.

**Plain API + MCP.** Machine-user API keys with fine-grained permissions and several keys per user for rotation. Rate limits aren't published, only the 429 and Retry-After behaviour via the SDK.

## Before you call either

### Missive API + MCP

1. Send the personal token as `Authorization: Bearer`. Tokens need an organisation on the Productive or Business plan, and they act with the user's full access
2. Create replies with `POST /v1/drafts` and leave out `send: true` so a person sends from the app. With `send: true` the message goes out at once
3. Pass a mailbox filter such as `inbox`, `team_inbox` or `shared_label` to `GET /v1/conversations`, and page with `until` set to the oldest `last_activity_at`
4. Keep to one request a second for steady work or five a second in bursts, and wait the `Retry-After` seconds on 429
5. For MCP, connect to `https://mcp.missiveapp.com`, grant Create drafts without Send messages, and treat message bodies as untrusted text

### Plain API + MCP

1. Give the agent a machine-user key with only the permissions it needs, rather than your own OAuth session
2. Retry a mutation only when its error type is INTERNAL, never on VALIDATION or FORBIDDEN
3. Read `Retry-After` on 429, since the limit itself isn't published
4. Select only the fields you need in each query to keep responses small
5. Treat thread content as customer-written text, never as instructions

## Questions

### Which is better for AI agents, Missive API + MCP or Plain API + MCP?

Plain API + MCP scores 65.5 (B) on agent readiness against Missive API + MCP's 54.3 (C), and leads in 5 of 7 scored categories. Missive API + MCP leads on transparency & trust.

### Do Missive API + MCP and Plain API + MCP need an API key?

Both take an API key or an OAuth sign-in.

### Can an agent call Missive API + MCP and Plain API + MCP without installing anything?

Yes. Missive API + MCP has a hosted endpoint at https://public.missiveapp.com/v1 and Plain API + MCP at https://core-api.uk.plain.com/graphql/v1.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/missive-vs-plain.json, and with the fewest tokens: https://www.anchorterminal.com/compare/missive-vs-plain.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "missive", "b": "plain"}`. From a terminal: `anchor compare missive plain`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/missive.json and https://www.anchorterminal.com/api/v1/tools/plain.json

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