GrowthBook vs Harness Feature Management & Experimentation

GrowthBook 40

No x402, MPP or L402 (0). Prices are public without a login. Pro is $40 a seat a month, with $10 per million CDN requests, $1 per GB and $30 per million Managed Warehouse events above the allowance; the $40 seat and $30 per million were re-read on 1 November (20). The Starter plan is free with "No credit card required", re-read on 1 November (20). A person signs up in a browser, then approves OAuth or creates a key (0). 0+20+20+0 = 40.

Harness Feature Management & Experimentation 15

No x402, MPP or L402 (0). No FME prices are published; harness.io/pricing lists FME only under Enterprise, priced by quotation (0). The docs describe a Start FME Free Plan step inside a Harness account; its limits and whether a card is needed aren't stated (15 of 20). A person signs up for Harness in a browser and creates a key or token (0). 0+0+15+0 = 15.

GrowthBook 75

The core and the MCP server are MIT. Three enterprise directories in the main repository are under GrowthBook's enterprise licence and are part of what Cloud runs (25 of 30). A Customer Agreement, a Privacy Notice of 8 June 2026 and a DPA of 19 June 2025 are published. The agreement grants GrowthBook an unrestricted right to use Customer Data, including to train its AI algorithms, then limits personal information to performing the Services. The Privacy Notice gives no retention periods, and the docs say only aggregate results are stored. We did not read the DPA, which is a download (16 of 30). Legacy v1 routes and 34 operations are marked deprecated with no removal dates, and no deprecation policy was found. The MCP changelog gives migration steps (8 of 20). The sub-processor list of 11 May 2026 names seven providers with locations, mostly in the United States. Notice of new ones is promised only as far as the law requires (17 of 20). 25+16+8+17 = 66. The legal documents are per the 8 October check, not re-read on 1 November.

Harness Feature Management & Experimentation 61

A closed service under Harness's subscription terms; the MCP server is MIT (18 of 30). The privacy statement covers website and sales data and defers customer data to the customer agreement and a published DPA; retention periods for customer data weren't found (18 of 30). A versioning policy for SDKs with support windows, and Split-era API endpoints marked deprecated with migration guides (14 of 20). Sub-processors are on the trust centre, which we didn't read, and the security page doesn't name data locations (10 of 20). 18+18+14+10 = 60.

GrowthBook 89

MCP server 2.2.0 is dated 5 October 2026 and published to the registry on 6 October, GrowthBook 5.1.0 was tagged on 21 September 2026, and the main repository's commit releasing the JavaScript and React SDKs 2.0.0 landed on 30 October (npm not readable from here) (30). In the 90 days from 3 August, GrowthBook 5.0.1 (19 August) and 5.1.0, MCP 2.1.0 (10 August) and 2.2.0, and the SDK 2.0.0 release commit (20). The main repository's 200 newest commits run from 5 to 30 October 2026, and there is a community Slack. We did not read how quickly issues are answered (15 of 25). io.github.growthbook/growthbook-mcp is in the official MCP registry at 2.2.0, published 6 October 2026 and still latest on 1 November (15). The MCP repository runs CI on Node 22 and 26 and took dependency updates on 8 and 27 October 2026, both still unreleased. The package states Node 18 or later, which CI does not test (9 of 10). 30+20+15+15+9 = 89.

Harness Feature Management & Experimentation 81

harness-mcp-v2 3.2.40 was tagged on 4 November 2026 (30). 14 tagged MCP releases between 8 August and 4 November (20). 100 commits since 8 August in the clone; FME docs and SDK release notes are dated, with support and a community site. Issue response times weren't read because the GitHub API refused us for its rate limit (15 of 25). Not found in the official MCP registry under a Harness namespace; official SDKs are current (8 of 15). MIT package with npm shrinkwrap and tests; CI state not read (8 of 10). 30+20+15+8+8 = 81.

GrowthBook 76

Four compact MCP tools, with skills loaded on demand and a /mcp/api endpoint that drops the skill tools (25). limit (default 10, maximum 100) and offset on 40 list operations, with filters by project, data source and status. No field selection was found, and the API tools return the raw response body (15 of 20). Errors are a status code and a message with no machine code. 422 marks a soft warning that can be resubmitted with ignoreWarnings, and the MCP server adds recovery hints for 401, 403, 404 and 429 (13 of 20). All four tools carry readOnlyHint and destructiveHint, and reads and writes are separate tools. Every write is marked destructive, and no idempotency keys were found (13 of 20). The API tools need one to three parameters. The SDKs cover flag evaluation in many languages, not the REST API (10 of 15). 25+15+13+13+10 = 76. Not re-read on 1 November beyond the MCP page and the spec, which still support each line.

Harness Feature Management & Experimentation 83

11 consolidated tools, and --toolsets=fme narrows the server to FME (25). Flag lists filter server-side by name, tag and rollout status, and the Admin API paginates with markerLimit (17 of 20). Documented status codes, 429 headers, and a harness_diagnose tool. Error bodies aren't documented per endpoint (14 of 20). harness_list and harness_get carry readOnlyHint, write tools ask for confirmation by elicitation, and harness_delete is marked destructive. No idempotency keys (15 of 20). Two required settings (API key, optional org and project, account ID read from the token); a Python Admin API wrapper and CLI, and SDKs in more than a dozen languages for evaluation (12 of 15). 25+17+14+15+12 = 83.

GrowthBook 86

Graded on GrowthBook Cloud with the hosted lines. Instatus page at status.growthbook.io with three components (GrowthBook Cloud App, Api, CDN) and a notice history (20). No notices from August to October 2026, and the newest entry in the feed, re-read on 1 November, is still dated 21 August 2025. The MCP server is not a listed component, and the 2.2.0 changelog fixes intermittent 502s in HTTP mode that were not posted, so 25 of 30. API keys are limited to 60 requests a minute on Cloud, re-read in the API introduction and the OpenAPI spec on 1 November; since 19 October self-hosted servers can set per-key limits (15). The docs say only to try again later on 429. The server source sends standard RateLimit headers and the MCP server waits for RateLimit-Reset and retries three times, but no backoff guidance or idempotency keys were found in the docs (8 of 15). The pricing page lists a 99.99 per cent uptime SLA on Enterprise, re-read on 1 November. The SLA document itself was not found in public (8 of 10). The REST API's /v1 is described as stable and the MCP docs carry no beta label (10). 20+25+15+8+8+10 = 86.

Harness Feature Management & Experimentation 80

Graded on the hosted FME Admin API with the hosted lines. Statuspage at status.harness.io with an FME component among 196 (20). In the 90 days from 8 August, two FME incidents: API write operations returned 499 errors for 30 minutes on 20 August (minor) and the FME user interface was unavailable for 15 minutes on 23 August (major, interface only; flag evaluation was unaffected per the post). No API outage of an hour or more (20 of 30). About 20 Admin API requests per 10 seconds per organisation and per IP, documented on the MCP page (15). 429 responses carry remaining and reset headers with guidance to wait for the larger reset, and the MCP server backs off and retries three times (15). No SLA was found on harness.io/pricing or the FME docs (0). FME is generally available and the MCP server is at 3.2.40 (10). 20+20+15+15+0+10 = 80.

GrowthBook 76

Public OpenAPI 3.1 spec, version 5.1.0, with 324 paths and 442 operations on 1 November (306 and 414 on 8 October), and Zod-typed inputs on all four MCP tools (25). llms.txt and a Markdown copy of each docs page (10). 441 of 442 operations have a summary and 205 have a description. The MCP tool descriptions say when to use each tool, and the bundled skills carry the workflows (13 of 20). The spec has 1,445 enums and marks required fields, but growthbook_api_write takes the path as a string and the body as a JSON string, and the docs still say the API tools do not validate payloads (9 of 15). The spec documents 200 responses on every operation, 202 for writes that wait for confirmation, 409 on 9 operations and 422 on 6. The introduction lists eight status codes and a message body (6 of 15). Path versions /v1 and /v2, 34 operations marked deprecated, GitHub releases, and an MCP changelog with breaking changes called out (13 of 15). 25+10+13+9+6+13 = 76.

Harness Feature Management & Experimentation 71

No public OpenAPI file for the Admin API was found; the reference is a ReadMe site with a Postman collection. The MCP server's 11 tools have typed inputs, and harness_describe returns each FME resource's fields (18 of 25). llms.txt on both developer.harness.io and docs.split.io, and every page as Markdown with .md (10). The README describes each tool and when writes ask for confirmation; resource details sit behind harness_describe rather than in the tool text (13 of 20). The generic tools take a resource_type string and a body, so per-resource constraints aren't in the schema (8 of 15). An error-code page lists 400, 401, 402, 403, 404, 409 and 429 with causes, and docs carry curl examples (10 of 15). Tagged MCP releases and dated SDK versioning policy; the Admin API has v1 and v2 paths and deprecation notices for Split-era endpoints (12 of 15). 18+10+13+8+10+12 = 71.