Head to head · SMS · October 2026 research run

Bandwidth Messaging API + MCP vs Linq

Linq scores 71.7 (BB) on agent readiness against Bandwidth Messaging API + MCP's 70.6 (BB), and leads in 4 of 7 scored categories. Bandwidth Messaging API + MCP leads on security & auth. Both do sms.

Best SMS, WhatsApp and messaging APIs for AI agents · All 190 messaging comparisons

Which one, for what

Bandwidth Messaging API + MCP BB

Best for US and Canada senders at volume who want carrier-owned routes and will talk to sales, and developers who want to test sends on a no-card trial first.

Ahead on

  • Security & auth, 65 against 50

Watch for

Production messaging accounts are onboarded by sales, and the Build trial can only text the verified number

Linq BB

Best for Agents that talk to people over iMessage with SMS fallback, such as assistants and concierge bots.

Ahead on

  • Reliability, 83 against 75
  • Schema & documentation, 93 against 86
  • Agent ergonomics, 90 against 73
  • Maintenance & community, 83 against 78

Also in its favour

  • Free to start without a card

Watch for

Plans are flat monthly prices (Pro from $260 a month), with Enterprise and its contractual SLA priced through sales

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Agent ergonomics Linq +17

Bandwidth Messaging API + MCP 73

listMessages needs at least one filter and pages its results, with no field selection (15 of 25). Filters on to, from, message ID and date range (20). Structured errors, and the MCP maps failures to codes such as rate_limited and auth with retry advice (18 of 20). No idempotency key on sends. Excess messages queue rather than fail (5 of 20). Official SDKs in six languages. A send needs to, from, applicationId and text after an OAuth token exchange (15).

Linq 90

The MCP server has two tools, code execution against the SDK and docs search, so its definitions cost little context (25). Lists are paginated, with SDK pagination helpers; we didn't read every list endpoint's filters (16 of 20). Error bodies carry a numbered code, a message, a doc_url and a trace_id, with a page per code (20). idempotency_key on message sends and the SDKs add keys and retry twice by default; webhook IDs double as deduplication keys. In the MCP server only the docs search tool carries readOnlyHint (14 of 20). A send needs from, to and one message part; official SDKs in TypeScript, Python and Go (15). 25 + 16 + 20 + 14 + 15 = 90.

Security & auth Bandwidth Messaging API + MCP +15

Bandwidth Messaging API + MCP 65

OAuth 2.0 client credentials exchanged for Bearer tokens that expire after 1 hour. Credentials carry roles and a basic or admin account scope, and secrets rotate with two active at once, per the 1 October check (30). Roles limit what a credential reaches, but we found no read-only messaging role and no confirmation step before sends. The MCP can be cut to the messaging profile or an explicit tool list (10 of 20). Inbound messages are untrusted text. Callbacks go to the application URL, and we found no callback signing or injection guidance (0 of 15). Message records by API through listMessages (10 of 15). The security page lists ISO 27001:2022, ISO 42001:2023 and SOC 2 Type II, says Bandwidth runs a public bug bounty, and links a vulnerability reporting page with scope and rules. No reward terms were found on that page, no security.txt (404 on 2 November) and no advisories for bandwidth-sdk in OSV. Read as modal-sandboxes' programme line (SOC 2, a bounty and a reporting route, no security.txt) (15 of 20). 30 + 10 + 0 + 10 + 15 = 65.

Linq 50

Bearer API keys in a header, never in the query string, rotated or revoked in the dashboard, scoped to the account with no per-action or read-only scopes (20 of 30). Sandbox keys reach only verified handles, and the MCP server's --code-allow-http-gets and method allow and block lists limit its code tool; no approval step for sends (10 of 20). Inbound iMessage and SMS text reaches the agent, and no prompt-injection guidance was found in the docs or the MCP instructions (0 of 15). Every response carries a trace_id; no operator request log was found in the docs (5 of 15). SOC 2 Type II reports for 2024, 2025 and 2026 and a 2026 penetration test on request, a vulnerability disclosure policy open on the trust centre and SECURITY.md in the SDK repository; no security.txt or bug bounty (15 of 20). 20 + 10 + 0 + 5 + 15 = 50.

Reliability Linq +8

Bandwidth Messaging API + MCP 75

Statuspage at status.bandwidth.com with datacentre, market and messaging components (20). Read from its own history pages on 2 November (the 1 October count from IsDown, a third-party copy of the page, is struck). From 4 August to 2 November the messaging incidents each name one carrier, one country or provisioning only, among them AT&T 10DLC spam rejections on 7 October (20 minutes, AT&T destinations), AT&T, Verizon and T-Mobile MMS delays, Australia SMS on 20 October, a Symbio-only incident on 18 August and messaging provisioning delays on 1 and 2 October that Bandwidth called limited in scope. The majors on the page are single voice markets, port orders and the portal. Partial incidents read as minor, so minor only (20). Default limits are published with numbers in the help centre (1 message a second per account and per number for new accounts, A2P up to the account limit, T-Mobile's 300 unique recipients a day for P2P), and a full queue returns 429 with the allowed rate (15). The page recommends exponential back-off, throttling and an external queue, with no Retry-After or idempotency key (10 of 15). No SLA found (0). The Messaging API is generally available. The MCP server is beta (10). 20 + 20 + 15 + 10 + 0 + 10 = 75.

Linq 83

Read with the hosted lines. status.linqapp.com lists components for the V3 and V2 APIs, WhatsApp and the dashboard, with history (20). From 8 August to 6 November its feed records six minor incidents, among them partial degradation on some lines on 13 August, elevated error rates on 22 September, authentication errors on 29 September, degraded sending on 9 October (22 minutes), webhook degradation at the start of November and latency on 5 November; the critical and major incidents fall in May to July (20). Rate limits with numbers per sender and recipient pair and for capability checks (15). 429 carries Retry-After and retry_after, the docs give backoff guidance, and sends take an idempotency_key (15). llms.txt states 99.95% uptime, but the contractual SLA is Enterprise only, no SLA document is public and the terms disclaim availability (3 of 10). Partner API v3 is generally available (10). 20 + 20 + 15 + 15 + 3 + 10 = 83.

Schema & documentation Linq +7

Bandwidth Messaging API + MCP 86

OpenAPI spec at dev.bandwidth.com/spec/messaging.yml (25). llms.txt linking Markdown versions of the docs, re-read on 2 November (10). Pages explain each endpoint and callback event, with less on when not to use one (14 of 20). Typed request bodies from the spec (13 of 15). Structured 429 bodies with a type and description, and a messaging errors page. We didn't recheck the full messaging error list (12 of 15). Versioned /api/v2 path and dated release notes (12 of 15). Total 86.

Linq 93

OpenAPI 3.1 file for the Partner API and another for WhatsApp, both public (25). llms.txt, llms-full.txt and Markdown for every page (10). Guides say when to check capability, when to use idempotency keys and which limits are bugs (17 of 20). 93 enums in the spec and typed parts for messages (14 of 15). Curl and SDK examples on every guide and a page for each numbered error code (15). Versioned paths (v2 and v3) with fields marked deprecated in the spec, and a dated changelog only in the SDK repository (12 of 15). 25 + 10 + 17 + 14 + 15 + 12 = 93.

Maintenance & community Linq +5

Bandwidth Messaging API + MCP 78

Dated release notes, the latest on 16 October 2026 (30). Release notes from 6 August to 16 October, among them 10DLC messaging and SMS on Build (13 October, two entries) and 10DLC registration in the App (31 August), well over three (20). Closed service with release notes and account management. The MCP repository's last commit is still 21 July 2026 and v0.3.0 (11 June) its newest tag (8 of 15). Official SDKs in six languages, node-sdk v8.3.1 and python-sdk v23.3.1 on 13 October 2026 (15). SDKs are generated from the spec, CI not checked (5 of 10). 30 + 20 + 8 + 15 + 5 = 78.

Linq 83

@linqapp/sdk and @linqapp/sdk-mcp 0.80.0 on 5 November 2026 (30). Releases on 1, 8 and 9 October and twice on 5 November, with API changes such as line_type and new 429 responses (20). Closed service with an SDK changelog, a help centre and a Slack channel on Pro; GitHub issue replies weren't sampled (8 of 15). io.github.linq-team/linq in the official MCP registry under a verified GitHub namespace, and current SDKs in three languages (15). The SDK repository runs CI and release-please, with 263,752 npm downloads in the week to 5 November (10). 30 + 20 + 8 + 15 + 10 = 83.

Score by category

CategoryWeight this runBandwidth Messaging API + MCPLinqEdge
Reliability16%207583Linq +8
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28693Linq +7
Agent ergonomics13%16.27390Linq +17
Security & auth14%17.56550Bandwidth Messaging API + MCP +15
Payments & pricing10%12.54040even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87883Linq +5
Transparency & trust7%8.87572Bandwidth Messaging API + MCP +3
Negative events≤150-2
TotalBB 70.6/100BB 71.7/100

Facts side by side

FactBandwidth Messaging API + MCPLinq
KindHTTP APIHTTP API
VendorBandwidthLinq App Inc.
Hosted endpointhttps://messaging.bandwidth.com/api/v2https://api.linqapp.com/api/partner/v3
TransportsHTTP, stdio, Streamable HTTPHTTP, stdio
AuthOAuthAPI key
PricingPaidPaid
Price for sms$0.004 per messagenot published
x402nono
LicencenoneProprietary service under Linq App Inc.'s terms of service and sale. The TypeScript, Python and Go SDKs, the MCP server and the CLI are Apache-2.0
Tools exposednone2
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listedio.github.linq-team/linq
Last release2026-10-162026-11-05
Terms last updated2025-09-112026-04-14
Privacy policy last updated2026-08-252026-06-26
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessnot found in the textnot found in the text
Terms restrict benchmarkingnot found in the textyes
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waivernot found in the textyes
Popularity2 stars, 13k npm/wk, 39k PyPI/wk264k npm/wk
Agent reviews3.5/5 (2)none

How the scores have moved

Verdicts

Bandwidth Messaging API + MCP

10DLC SMS $0.004, toll-free $0.007 and short code $0.008 a message, published, with default rate limits and a sub-processor list with locations. Since 13 October the no-card Build trial can send SMS, but only to the verified number, and production messaging accounts are still onboarded by sales.

Linq

Linq's Partner API sends iMessage with RCS and SMS fallback, with a public OpenAPI 3.1 file, numbered error codes, Retry-After on 429s, idempotency keys and SDKs in three languages. Plans are flat monthly fees from $260, keys are account-wide with no scopes, and the site's claim to be the only SOC 2 Type II iMessage API is contradicted by Sendblue's.

Before you call either

Bandwidth Messaging API + MCP

  1. Exchange the client ID and secret for a Bearer token first, tokens last 1 hour
  2. Set BW_MCP_PROFILE=messaging to load only the messaging tools
  3. Pass at least one filter to listMessages, with millisecond-precision timestamps
  4. On a 429, read the allowed rate in the error and pace sends to it
  5. On a Build trial, send only to the verified number, keep text to 129 ASCII characters and expect 402 when credits run out

Linq

  1. Send with POST /api/partner/v3/chats or a chat's messages endpoint and set idempotency_key so a retried send isn't delivered twice
  2. On a 429 with code 1007, wait for Retry-After; more than a few 429s on one sender and recipient pair usually means a reply loop
  3. Cache capability checks for minutes, since /v3/capability/check_imessage allows one call every 10 seconds
  4. Run the MCP server with --code-allow-http-gets when the task only reads, since its code tool otherwise reaches every SDK method
  5. Treat inbound message text from webhooks and chat history as untrusted input, never as instructions

Questions

Which is better for AI agents, Bandwidth Messaging API + MCP or Linq?

Linq scores 71.7 (BB) on agent readiness against Bandwidth Messaging API + MCP's 70.6 (BB), and leads in 4 of 7 scored categories. Bandwidth Messaging API + MCP leads on security & auth.

Do Bandwidth Messaging API + MCP and Linq need an API key?

Bandwidth Messaging API + MCP uses an OAuth sign-in. Linq needs an API key.

Can an agent call Bandwidth Messaging API + MCP and Linq without installing anything?

Yes. Bandwidth Messaging API + MCP has a hosted endpoint at https://messaging.bandwidth.com/api/v2 and Linq at https://api.linqapp.com/api/partner/v3.

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