Best of · Work & business apps
Best agent tool access platforms
All 8 ranked agent tool access platforms on the Anchor benchmark, with a pick for each need and where each one falls short. Scores come from public evidence, re-checked as vendors change.
- 8 ranked
- 1 agent-ready
- 8 hosted endpoints
- Updated 9 October 2026
Top three
Picks by need
Worked out from the scores, prices and facts, so they change when the research does.
Our own products are ranked like any listing but are never a pick.
The shortlist
| # | Tool | Grade | Best for | Price | Where |
|---|---|---|---|---|---|
| 1 | Composio (API + MCP) Composio |
BB 75.1 | A developer whose agent acts in many apps for many end users and wants auth, tool schemas and execution handled. | $29 / mo | hosted |
| 2 | Merge Agent Handler Merge API, Inc. |
B 69.5 | A product team whose agent acts in customers' SaaS accounts and needs per-user credentials, key scoping, redaction rules and logs in one hosted layer, and teams already on Merge's Unified API. | $1000 / mo | hosted |
| 3 | StackOne StackOne Technologies Limited |
B 69.1 | A company that wants one governed MCP endpoint for staff agents across business systems, and product teams embedding per-customer connections with HR, recruiting and CRM coverage. | $600 / mo | hosted |
| 4 | One One Systems, Inc. |
B 66.6 | A person or small team that wants one MCP entry with a small tool footprint across many SaaS accounts, with access set per connection and a free plan. | $29 / mo | hosted and local |
| 5 | Unified.to MCP Server Unified API Inc. |
C 61.9 | A B2B software team that already uses or plans to use Unified's API and wants the same customer connections exposed to an LLM, with data read live from the source app. | $750 / mo | hosted |
| 6 | Zapier MCP (agent actions) Zapier |
C 58.1 | Best when an agent needs one-off actions across many SaaS apps that a person has already connected in Zapier. | Your plan | hosted |
| 7 | Smithery Smithery (Arcade.dev) |
D 50.7 | A developer who wants many MCP servers behind one credential and one endpoint, with per-user connections and short-lived scoped tokens. | Freemium | hosted |
| 8 | letme Anchor Terminal |
F 36.4 | An agent that knows the job but not the tool and wants one recommendation picked by a published rule, with the direct call details and fallbacks by not=. | Free | hosted |
How to choose
- Per end-user authorisationCheck that each end user authorises their own connections, so one person's email or CRM access is never reused for another person's agent session.
- Context footprint of toolsCheck how many actions and schema fields are sent to the model on each call, since a large tool list uses context before the agent does any work.
- Action coverage for the taskCheck that the email, CRM and database actions a task needs are all listed, since a missing action forces a custom integration partway through the job.
- Logs of each delegated callCheck whether each call is logged with the end user it ran for, so an operator can trace which person's account an agent used and when.
How the benchmark tests this category. The same task across email, CRM and a database, driven by an agent through each service. We compare connection setup, how each end user authorises, action coverage, retries, logs and the cost per completed run.
Each one in detail
Composio (API + MCP)
BB 75.1/100Tool access and per-user authentication for agents across 1,000+ apps.
Verdict Connect supports toolkit selection and filtering by read-only or destructive actions. Rube closed on 16 May 2026, so existing rube.app configurations need migration.
Choose it for A developer whose agent acts in many apps for many end users and wants auth, tool schemas and execution handled.
Strengths
- Seven Connect meta-tools, and sessions that load chosen toolkits or filter by read-only and destructive tags
- Per-call prices in public and 100,000 free tool calls a month with no card
- OpenAPI 3.0 with 62 paths, llms.txt and an error reference
Weaknesses
- Rube shut down on 16 May 2026, so old rube.app configs are dead
- Tool arguments and responses are logged for up to a year unless ZDR, a paid add-on, is on
- The sandbox with remote Python and bash is on by default in sessions
Price $29 / moAuth OAuth or keyx402 nohosted
Merge Agent Handler
B 69.5/100Merge Agent Handler is a hosted MCP server from Merge API, Inc. that gives AI agents tools across more than 190 third-party connectors, with per-user credentials, tool packs, a security gateway and logs of every call.
Verdict Agent Handler's access keys can be limited to named users, tool packs and a runtime scope, with an expiry, and an agent can create an account with one documented request. No rate limit figures are published, Pro starts at $1,000 a month with no published overage rate, and failed or blocked calls spend credits.
Choose it for A product team whose agent acts in customers' SaaS accounts and needs per-user credentials, key scoping, redaction rules and logs in one hosted layer, and teams already on Merge's Unified API.
Strengths
- Access keys can be limited to named Registered Users and Tool Packs and to the
runtime:allscope, with an expiry. A child key is never wider than its parent - The docs and OpenAPI file describe
POST /api/v1/agent/signup/, which needs no credentials and returns a key, a tool pack and a registered user - The Free plan has 2,000 credits a month, one per tool call, and the quickstart says signup needs no card
Weaknesses
- No rate limit figures are published. The docs say only that MCP tool calls are limited per Registered User and per organisation, by the minute
- Pro starts at $1,000 a month for 25,000 credits, and the overage rate isn't on the pricing page
- Every
tools/callspends a credit, including failed calls, calls blocked by a rule and calls made with a test key
Price $1000 / moAuth OAuth or keyx402 nohosted
StackOne
B 69.1/100StackOne is a hosted gateway from StackOne Technologies Limited that gives AI agents actions across more than 540 business apps over MCP, SDKs, A2A or HTTP, with managed authentication, per-user grants, policies and logs.
Verdict StackOne's MCP server signs each person in with OAuth, lets them grant individual accounts and actions, and by default exposes two search and execute tools in place of the full catalogue. Session token URLs carry the credential in the query string for a year by default, and the Consumption Schedule and pricing page disagree on whether failed calls are billed.
Choose it for A company that wants one governed MCP endpoint for staff agents across business systems, and product teams embedding per-customer connections with HR, recruiting and CRM coverage.
Strengths
- The MCP server at
https://mcp.stackone.com/mcpuses OAuth per person. Access tokens last one hour, a grant lasts 90 days, and each user can revoke it under Connected Apps - Advanced Tool Search replaces the tool list with two tools, search and execute, and is on by default at the OAuth consent screen
- Since 24 July 2026 every tool carries
readOnlyHint,destructiveHintandopenWorldHint, derived from an effects value on each action
Weaknesses
- Session token URLs (
https://api.stackone.com/mcp?token=...) put the credential in the query string, cover one linked account and expire after one year by default - The Service Consumption Schedule counts every request, successful or not, as an Action Call. The pricing page says failed calls aren't billed
- Defender's default mode is Monitor, which records a verdict and passes the tool result to the agent unchanged
Price $600 / moAuth OAuth or keyx402 nohosted
One
B 66.6/100One is a hosted MCP server and CLI from One Systems, Inc. (formerly Pica) that lets AI agents find and run actions in a user's connected apps, with credentials held by One and access scoped per connection.
Verdict One's remote MCP server has three tools, OAuth 2.1 sign-in with PKCE and a consent screen that sets read only, read and write, full or per-action access for each connection. A person must sign in through a browser, the SOC 2 audit is unfinished, and the site's changelog stops at 13 July 2026.
Choose it for A person or small team that wants one MCP entry with a small tool footprint across many SaaS accounts, with access set per connection and a free plan.
Strengths
- The remote server has three tools whatever the number of connections, and
find_one_actionsreturns large documents as a digest with sections loaded on request - The consent screen sets Full access, Read & write, Read only or a ticked list of actions per connection, and One enforces the grant on every call
- Access tokens last one hour, and changing or revoking a grant in the dashboard applies on the agent's next call
Weaknesses
- The remote server's tools changed from four to three by 30 September 2026, and the site's changelog, last dated 13 July 2026, has no entry for it
- The home and security pages say nothing from a call is stored. The privacy policy says request logs may include integration payloads, kept 14 to 90 days by default
- The SOC 2 audit is described as in progress,
/.well-known/security.txtreturned 404, and no bug bounty or published advisories were found
Price $29 / moAuth OAuth or keyx402 nohosted and local
Unified.to MCP Server
C 61.9/100Unified.to MCP Server is a hosted Streamable HTTP server from Unified API Inc. that turns one end-customer connection to a business app into MCP tools, on top of the vendor's unified API for CRM, HR, accounting and other categories.
Verdict Every previewed tool carries a typed input schema and read-only, destructive and idempotent annotations, and the list can be narrowed by permission or tool name. The default credential is a workspace API key that reaches every connection, and the SSE transport was removed on 23 September 2026 in the changelog entry that announced it.
Choose it for A B2B software team that already uses or plans to use Unified's API and wants the same customer connections exposed to an LLM, with data read live from the source app.
Strengths
- A credential-free preview of the HubSpot tool list returned 78 tools, each with a JSON Schema input and
readOnlyHint,destructiveHintandidempotentHintannotations, and 66 with an output schema - The
permissionsandtoolsURL parameters limit which tools a connection lists, andhide_sensitivestrips names, emails and telephone numbers from results - A
usermode URL carries a signed token limited to one connection, so the workspace API key need not be shared with an end customer
Weaknesses
- The default credential is a workspace API key. The docs say it grants access to all connections and the whole Unified.to account
- The
/ssetransport and thesse_urlresponse field were removed on 23 September 2026. No earlier notice was found in the MCP changelog, the site changelog or the September update - The connection-scoped signed token travels in the URL as
?token=. The docs mark?token=authentication as deprecated, with no end date set
Price $750 / moAuth OAuth or keyx402 nohosted
Zapier MCP (agent actions)
C 58.1/100Hosted MCP server that lets agents discover and run actions across apps connected to the user's Zapier account.
Verdict 16 meta-tools in agentic mode, or managed mode with only the actions you pick. Connection tokens are long-lived and the docs allow them in the URL query string.
Choose it for Best when an agent needs one-off actions across many SaaS apps that a person has already connected in Zapier.
Strengths
- 16 meta-tools in agentic mode, or managed mode with only the actions you pick
- Failed calls and discovery are free, and each successful call costs two tasks
- An MCP component on the status page and per-call activity logs for the user
Weaknesses
- Connection tokens are long-lived and the docs allow them in the URL query string
- No numeric rate limits and no retry guidance when the task cap is hit
- Only Enterprise is opted out of AI training and gets configurable retention
Price Your planAuth OAuth or keyx402 nohosted
Smithery
D 50.7/100Smithery is a hosted registry and connection service for MCP servers, part of Arcade.dev since August 2026. Agents search the registry, create connections and call tools through a REST API, a per-namespace MCP endpoint, a TypeScript client or a CLI.
Verdict Service tokens can be limited by namespace, resource, operation and connection metadata, with a lifetime of at most 24 hours. No terms of service, rate limits or SLA were found, the pricing page could not be read, and the newest client release is from 20 July 2026.
Choose it for A developer who wants many MCP servers behind one credential and one endpoint, with per-user connections and short-lived scoped tokens.
Strengths
- Service tokens are scoped by namespace, resource, operation (read, write, execute) and connection metadata, expire within 24 hours and can be narrowed further
- An OpenAPI 3.1 file with 55 operations,
/docs/llms.txtand a Markdown twin of every docs page - Connections report
auth_requiredorinput_requiredwith a hostedsetupUrland the list of missing fields
Weaknesses
- No terms of service are linked from the site, the docs or the footer. The privacy notice of 20 June 2025 is the only legal document found
- The privacy notice links a Data Policy at
/docs/use/data-policy, which answers 404 - No rate limits, 429 response or SLA appear in the docs or the API description
Price FreemiumAuth OAuth or keyx402 nohosted
letme
F 36.4/100letme.dev selects tools for a task using Anchor Terminal's grades.
Verdict No key, account or card to ask for a pick, over GET, POST or MCP, and every address we called answered without credentials. Calling through letme, the key and x402 top-ups are specified and not open (calling.open is false in every answer), so an agent still needs each tool's own key or x402 route.
Choose it for An agent that knows the job but not the tool and wants one recommendation picked by a published rule, with the direct call details and fallbacks by not=.
Strengths
- No key, account or card to ask for a pick, over GET, POST or MCP, and every address we called answered without credentials
- OpenAPI 3.1, llms.txt and an Agent Skill linked from llms.txt describe the same ten filters and the 400, 404 and 503 answers
- Each answer reports a self-check, 283 of 283 picks recomputed and agreeing on 2 October 2026, and the pick rule and word table are published
Weaknesses
- Calling through letme, the key and x402 top-ups are specified and not open (calling.open is false in every answer), so an agent still needs each tool's own key or x402 route
- No status page, no published rate limit for picking, no 429 guidance and no SLA, and the limits on /letme/ belong to a key that isn't issued
- Closed source, no SDK and no MCP registry entry, and the GitHub link on /letme/ and /about/ answers 404
Price FreeAuth Nonex402 nohosted
Full assessment · Against #1, Composio (API + MCP)
Disclosure letme is Anchor Terminal's own product, run by the same company and founder. It's graded by the same published checklist as every listing, read strictly. Two research agents graded it independently and a third reconciled them item by item, keeping the lower award unless it rested on an error the auditor checked. letme never picks it. Since 5 October 2026 the review panel reviews it like any listing, told that it's our own product and to be neither kinder nor harsher.
Head to head
- Composio (API + MCP) vs Merge Agent Handler BB 75.1 vs B 69.5
- Composio (API + MCP) vs StackOne BB 75.1 vs B 69.1
- Composio (API + MCP) vs One BB 75.1 vs B 66.6
- Composio (API + MCP) vs Unified.to MCP Server BB 75.1 vs C 61.9
- Merge Agent Handler vs StackOne B 69.5 vs B 69.1
- Merge Agent Handler vs One B 69.5 vs B 66.6
- Merge Agent Handler vs Unified.to MCP Server B 69.5 vs C 61.9
- One vs StackOne B 66.6 vs B 69.1
- StackOne vs Unified.to MCP Server B 69.1 vs C 61.9
- One vs Unified.to MCP Server B 66.6 vs C 61.9
Questions
What are the highest-rated agent tool access platforms for AI agents?
Composio (API + MCP) has the highest benchmark score of the 8 ranked agent tool access platforms, 75.1 (BB). Merge Agent Handler is second with 69.5 (B).
How many agent tool access platforms are agent-ready?
1 of the 8 ranked here grade BB or better, the bar for agent-ready on the Anchor benchmark.
Which agent tool access platforms accept x402 payments?
None of the ranked listings here accepts x402 for its main call yet.
How is this list ranked?
By the Anchor benchmark score out of 100, a weighted mean of the scored categories minus deductions for negative events, from public evidence re-checked as vendors change. Listings cannot pay for a place. The latest assessment behind this page is from 9 October 2026.
How this list is made
The order is the Anchor benchmark score, the same number as on each listing and in the top list. Each listing is graded from public evidence against the benchmark checklist, and the picks above are worked out from those grades, prices and facts. No listing pays for its place, and paid audits or listing help never change a score.
Full ranked table · 28 head-to-head comparisons · Best tools in every category