# Harness Feature Management & Experimentation vs Mostly Good Metrics (slim)

> Harness Feature Management & Experimentation scores 69.2 (B) to Mostly Good Metrics's 41.7 (E) for feature flags and experiments. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/harness-fme-vs-mostly-good-metrics.md (~5,000 tokens) · this version ~2,730 tokens · JSON https://www.anchorterminal.com/compare/harness-fme-vs-mostly-good-metrics.json · canonical https://www.anchorterminal.com/compare/harness-fme-vs-mostly-good-metrics
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-07
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

Harness Feature Management & Experimentation scores 69.2 (B) on agent readiness against Mostly Good Metrics's 41.7 (E), and leads in 6 of 7 scored categories. Mostly Good Metrics leads on payments & pricing. Both do feature flags and experiments.

- Harness Feature Management & Experimentation: B 69.2, rank #257 of 1486 · https://www.anchorterminal.com/tools/harness-fme.min.md
- Mostly Good Metrics: E 41.7, rank #1277 of 1486 · https://www.anchorterminal.com/tools/mostly-good-metrics.min.md
- Harness Feature Management & Experimentation, good for Teams already on Harness, or Split customers, who want agents to inspect and change flags and segments with guard rails. Ahead on Reliability, 80 against 29; Schema & documentation, 71 against 49; Agent ergonomics, 83 against 49; Security & auth, 79 against 33; Maintenance & community, 81 against 74; Transparency & trust, 61 against 45. Also Runs on your own machine.
- Mostly Good Metrics, good for Indie and small-team apps that want simple funnels and retention an agent can query. Ahead on Payments & pricing, 30 against 15. Also Free to start without a card.

| Category | Harness Feature Management & Experimentation | Mostly Good Metrics |
| --- | --- | --- |
| Reliability (16%) | 80 | 29 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 71 | 49 |
| Agent ergonomics (13%) | 83 | 49 |
| Security & auth (14%) | 79 | 33 |
| Payments & pricing (10%) | 15 | 30 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 81 | 74 |
| Transparency & trust (7%) | 61 | 45 |

| Fact (where they differ) | Harness Feature Management & Experimentation | Mostly Good Metrics |
| --- | --- | --- |
| Vendor | Harness Inc. | Mostly Good Metrics |
| Hosted endpoint | `https://mcp.harness.io/mcp` | `https://app.mostlygoodmetrics.com/mcp` |
| Transports | HTTP, stdio, Streamable HTTP | HTTP, Streamable HTTP |
| Tools exposed | 11 | 53 |
| llms.txt | yes | no |
| Last release | 2026-11-04 | 2026-10-16 |
| Terms last updated | no date given | 2025-12-01 |
| Privacy policy last updated | no date given | 2025-12-01 |
| Terms restrict benchmarking | yes | not found in the text |
| Popularity | 8.8k npm/wk | 81 npm/wk |

Why the edge:
- Reliability, Harness Feature Management & Experimentation +51: 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.); Mostly Good Metrics 29 (Graded on the hosted service with the hosted lines. No status page was found (0) and no incident history could be read (5). Ingestion limits are documented per plan (1,000 to 100,000 events a minute and 10,000 to 1,000,000 an hour), but no limit for MCP or query calls was found (12 of 15). 429 with Retry-After in the header and body, and the SDKs queue events and back off. No idempotency or safe-retry guidance for writes (12 of 15). No SLA (0). The press kit calls the product a public beta (0). 0+5+12+12+0+0 = 29.)
- Security & auth, Harness Feature Management & Experimentation +46: Harness Feature Management & Experimentation 79 (Admin API keys with combinable roles that can't be widened after creation, Harness PATs and SATs for central management, and Harness Platform OAuth on the hosted MCP endpoint. Credentials travel in headers (28 of 30). HARNESS_READ_ONLY removes every write, writes go through elicitation with a risk threshold for auto-approval, and FME change requests add approval for flag changes (19 of 20). No prompt-injection guidance; the tools return flag names, descriptions and rule data written by people (3 of 15). FME admin, environment and object audit logs, plus structured MCP audit events to file, webhook or OpenTelemetry sinks (13 of 15). SOC 1 and SOC 2 Type II, ISO 27001, 27017 and 27018, FedRAMP 20x, a security@harness.io disclosure route with a 24-hour response, a private bug bounty on request and annual external penetration tests. No security.txt (16 of 20). 28+19+3+13+16 = 79.); Mostly Good Metrics 33 (OAuth 2.0 with PKCE, dynamic client registration and a revocation endpoint for MCP and the CLI; project ingest keys in a Bearer header that can be pinned to origins or app IDs. The only tool scope advertised is mcp:tools, so a connection gets every tool the user can use (24 of 30). Restricted keys and a confirmation step for unrestricted keys in the CLI; no read-only MCP mode or approval for deletes was found (6 of 20). Event properties come from apps and end users and reach the agent, and no prompt-injection guidance was found (3 of 15). No audit log was found (0). No security.txt, disclosure policy or certification was found (0). 24+6+3+0+0 = 33.)
- Agent ergonomics, Harness Feature Management & Experimentation +34: 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.); Mostly Good Metrics 49 (53 tools, more than 30 (5). We added 3 because Goals and Alerts tools load only where enabled and query_metrics batches up to 10 queries (8 of 25). Date ranges, grouping and filters on queries; no documented page or limit parameters for lists (12 of 20). JSON errors with a message, and per-item status in batch results (13 of 20). Annotations weren't readable without a session, the tool list includes deletes and key revocation, and no idempotency keys were found (4 of 20). Five client SDKs and a CLI with `--json` output (12 of 15). 8+12+13+4+12 = 49.)
- Schema & documentation, Harness Feature Management & Experimentation +22: 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.); Mostly Good Metrics 49 (No OpenAPI file was found. The docs say every MCP tool describes its own parameters, and the query definition object is documented in full; we didn't open an MCP session to read the schemas (12 of 25). No llms.txt (404) and no Markdown pages served for agents (0). Each tool area is documented with examples, and the docs say when to use query_metrics instead of repeated execute_query calls (10 of 20). The query definition lists metrics, dimensions, date ranges and filter operators (9 of 15). The ingestion API documents its error body and status codes, and query_metrics reports per-item errors (11 of 15). /v1 and /api/v2 paths and dated SDK tags, but no product changelog (7 of 15). 12+0+10+9+11+7 = 49.)
- Transparency & trust, Harness Feature Management & Experimentation +16: 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.); Mostly Good Metrics 45 (The service is closed; the SDKs and CLI are MIT. Terms of December 2025 with no legal entity named (18 of 30). The privacy policy and terms agree on raw-event retention for the subscription's life and deletion within 14 days of account deletion; the about page says data is not used to train models. No DPA was found (18 of 30). The legacy X-MGM-Key header is still supported, and no deprecation policy was found (3 of 20). The terms name eight sub-processors with their purpose, without data locations (12 of 20). 18+18+3+12 = 51.)
- Payments & pricing, Mostly Good Metrics +15: 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.); Mostly Good Metrics 30 (No x402, MPP or L402 (0). Plan prices with event allowances are on the home page; no per-event price (10). Free plan with no card, stated on the home and about pages (20). Signup and OAuth approval happen in a browser (0). 0+10+20+0 = 30.)