HEAD TO HEAD
Harmonic Security matched with Prompt Security (SentinelOne): agentic endpoint security compared
SHORT ANSWER
On our published weights Harmonic Security scores higher overall, 5.90 to 5.45 out of 10. Harmonic scores higher on stop before it runs, capability rules, actor trail and rollout path; Prompt Security scores higher on cloud and workspace reach, named agent coverage and public proof; they tie on verdict range. Which fits depends on which of those criteria matters most to you.
By The Agent Desk · Agentic Endpoint Compare · Published 2026-10-11
Desk research from public vendor pages, press releases and standards pages read on 27 September and 11 October 2026. Editorial assessment; we did not run the products.
How do they compare at a glance?
Harmonic Security
Coaching people through AI data risk
Rank 6 of 8 among broader AI security platforms
Prompt Security (SentinelOne)
SentinelOne (deal announced 5 August 2025; completion reported in September 2025)
SentinelOne Singularity estates
Rank 8 of 8 among broader AI security platforms
Which scores higher on each criterion?
| Criterion | Weight | Harmonic Security | Prompt Security (SentinelOne) | Higher |
|---|---|---|---|---|
| Stop before it runs | 25% | 7 / 10 Governs at the MCP layer and at the tool surface and can block in real time. Source: Harmonic Security: Harmonic Command · Read 27 Sep 2026 | 6 / 10 Governs what agents and MCP servers can do; per-tool-call enforcement is not detailed. Source: SentinelOne: Prompt Security, securing AI · Read 27 Sep 2026 | Harmonic |
| Verdict range | 15% | 3 / 10 Documents 2 of six verdict types: Block or deny and Alert or warn. "Block in real time, warn the employee with context, or log silently." Source: Harmonic Security homepage · Read 27 Sep 2026 | 3 / 10 Documents 2 of six verdict types: Block or deny and Mask or modify. "Prevents prompt injection and data leakage; its browser extension inspects and redacts prompts." Source: SentinelOne: Prompt Security, securing AI · Read 27 Sep 2026 Source: Prompt Security blog: browser and endpoint sensors (updated 16 August 2026) · Read 11 Oct 2026 | Tie |
| Capability rules | 15% | 7 / 10 Harmonic Command sets which systems agents can read, write to and act on. Source: Harmonic Security: Harmonic Command · Read 27 Sep 2026 | 5 / 10 Maps agents and MCP servers and finds shadow MCP servers; capability rules are not itemized. Source: SentinelOne: Prompt Security, securing AI · Read 27 Sep 2026 | Harmonic |
| Actor trail | 10% | 6 / 10 Unified governance for people and agents; per-action attribution is not detailed. Source: Harmonic Security: Harmonic Command · Read 27 Sep 2026 | 5 / 10 Agent versus person attribution is not described on the pages we read. Source: SentinelOne: Prompt Security, securing AI · Read 27 Sep 2026 | Harmonic |
| Rollout path | 10% | 8 / 10 Rolls out through Intune, JAMF, Kandji or Group Policy. Source: Harmonic Security homepage · Read 27 Sep 2026 | 6 / 10 Two resident sensors, a browser extension and a dedicated AI endpoint agent, inside the SentinelOne Singularity Platform. Source: Prompt Security blog: browser and endpoint sensors (updated 16 August 2026) · Read 11 Oct 2026 | Harmonic |
| Cloud and workspace reach | 10% | 4 / 10 Browser, desktop, CLI, MCP gateway and API surfaces; agents running in cloud workspaces or cloud apps are not described. Source: Harmonic Security homepage · Read 27 Sep 2026 | 6 / 10 Covers homegrown AI apps from testing to runtime as well as employee and developer AI use. Source: SentinelOne: Prompt Security, securing AI · Read 27 Sep 2026 | Prompt Security |
| Named agent coverage | 5% | 3 / 10 Names 2 of the six agents we track: Claude Code and GitHub Copilot. Source: Harmonic Security pricing (re-read 11 October 2026) · Read 11 Oct 2026 | 5 / 10 Names 3 of the six agents we track: Claude Code, Cursor and GitHub Copilot. Source: SentinelOne: Prompt Security, securing AI · Read 27 Sep 2026 | Prompt Security |
| Public proof | 10% | 7 / 10 Tier names are published (Explore, Guide, Command) but no prices. Source: Harmonic Security pricing · Read 27 Sep 2026 | 8 / 10 Backed by SentinelOne, which announced the acquisition on 5 August 2025; pricing not published. Source: SentinelOne press release: agreement to acquire Prompt Security (5 August 2025) · Read 27 Sep 2026 | Prompt Security |
Which verdicts does each document?
| Verdict type | Harmonic Security | Prompt Security (SentinelOne) |
|---|---|---|
| Block or deny | Documented | Documented |
| Ask a person | Not described | Not described |
| Alert or warn | Documented | Not described |
| Mask or modify | Not described | Documented |
| Simulate first | Not described | Not described |
| Remove or scale back | Not described | Not described |
- Harmonic Security: "Block in real time, warn the employee with context, or log silently."
Source: Harmonic Security homepage · Read 27 Sep 2026
- Prompt Security (SentinelOne): "Prevents prompt injection and data leakage; its browser extension inspects and redacts prompts."
Source: SentinelOne: Prompt Security, securing AI · Read 27 Sep 2026
Source: Prompt Security blog: browser and endpoint sensors (updated 16 August 2026) · Read 11 Oct 2026
How does each reach devices?
Harmonic Security
Intune, JAMF, Kandji or Group Policy.
Source: Harmonic Security homepage · Read 27 Sep 2026
Prompt Security (SentinelOne)
Two local sensors, a browser extension and a dedicated AI endpoint agent, built into the SentinelOne Singularity Platform.
Source: Prompt Security blog: browser and endpoint sensors (updated 16 August 2026) · Read 11 Oct 2026
Which agents does each name?
| Agent | Harmonic Security | Prompt Security (SentinelOne) |
|---|---|---|
| Claude Code | Named | Named |
| Cursor | Not named | Named |
| GitHub Copilot | Named | Named |
| OpenAI Codex | Not named | Not named |
| Windsurf | Not named | Not named |
| Claude Desktop | Not named | Not named |
| Named | 2 of 6 | 3 of 6 |
Which should you choose?
Choose Harmonic Security if you need rollout path and stop before it runs. Harmonic Security is best for: Coaching people through AI data risk.
Choose Prompt Security (SentinelOne) if you need public proof and stop before it runs. Prompt Security (SentinelOne) is best for: SentinelOne Singularity estates.
Frequently asked questions
Which is better for agentic endpoint security, Harmonic Security or Prompt Security (SentinelOne)?
On our published weights Harmonic Security scores higher overall, 5.90 to 5.45 out of 10. See the criterion table above for where each scores higher.
Which stops an agent action before it runs more fully, Harmonic Security or Prompt Security (SentinelOne)?
Harmonic Security scores higher on stopping an action before it runs (7 to 6). Harmonic Security: Governs at the MCP layer and at the tool surface and can block in real time. Prompt Security (SentinelOne): Governs what agents and MCP servers can do; per-tool-call enforcement is not detailed.
Do Harmonic Security and Prompt Security (SentinelOne) publish prices?
Harmonic Security: not published. Three tiers are named (Explore, Guide, Command); prices are not published. Prompt Security (SentinelOne): not published. SentinelOne publishes no pricing for Prompt Security.