# hippo_corpus_diff

FORGIA #218 — timeline of changes across the 3 memory

Agent View of the PolicyLayer registry record for `hippo_corpus_diff`. HTML page: https://policylayer.com/tools/verimem/hippo-corpus-diff

## Facts

- Tool: `hippo_corpus_diff`
- Server: Verimem (`aureliocpr-ctrl/verimem`) — https://policylayer.com/tools/verimem.md
- Homepage: https://github.com/aureliocpr-ctrl/verimem
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "hippo_corpus_diff",
    "arguments": {}
  }
}
```

## Why hippo_corpus_diff is rated Low

This tool retrieves a timeline or audit trail of memory changes rather than creating, executing code, destroying data, or moving money. While access to change histories could expose sensitive patterns in what has been modified (moderate information disclosure risk), the operation itself is fundamentally a read/query function.

From the tool's own definition: "Tool name 'hippo_corpus_diff' and description 'timeline of changes across the 3 memory' indicate querying/retrieving historical change data."

## Use case

AI agents call hippo_corpus_diff to retrieve information from Verimem without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches Verimem:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "hippo_corpus_diff": {}
  }
}
```

## Other tools on Verimem (236)

- `hippo_fact_forget` — Destructive — https://policylayer.com/tools/verimem/hippo-fact-forget.md
- `hippo_fact_forget_with_undo` — Destructive — https://policylayer.com/tools/verimem/hippo-fact-forget-with-undo.md
- `hippo_forget` — Destructive — https://policylayer.com/tools/verimem/hippo-forget.md
- `hippo_forget_scope` — Destructive — https://policylayer.com/tools/verimem/hippo-forget-scope.md
- `hippo_skill_archive` — Destructive — https://policylayer.com/tools/verimem/hippo-skill-archive.md
- `hippo_skill_retire` — Destructive — https://policylayer.com/tools/verimem/hippo-skill-retire.md
- `hippo_compose_plan` — Execute — https://policylayer.com/tools/verimem/hippo-compose-plan.md
- `hippo_consolidate` — Execute — https://policylayer.com/tools/verimem/hippo-consolidate.md
- `hippo_curate_pipeline` — Execute — https://policylayer.com/tools/verimem/hippo-curate-pipeline.md
- `hippo_decay_run` — Execute — https://policylayer.com/tools/verimem/hippo-decay-run.md
- `hippo_plan_strips` — Execute — https://policylayer.com/tools/verimem/hippo-plan-strips.md
- `hippo_provider_switch` — Execute — https://policylayer.com/tools/verimem/hippo-provider-switch.md
- `hippo_reason` — Execute — https://policylayer.com/tools/verimem/hippo-reason.md
- `hippo_rollout_actions` — Execute — https://policylayer.com/tools/verimem/hippo-rollout-actions.md
- `hippo_run_task` — Execute — https://policylayer.com/tools/verimem/hippo-run-task.md
- `hippo_skill_compile_macro` — Execute — https://policylayer.com/tools/verimem/hippo-skill-compile-macro.md
- `hippo_skill_derive_predicates` — Execute — https://policylayer.com/tools/verimem/hippo-skill-derive-predicates.md
- `hippo_skills_derive_predicates_batch` — Execute — https://policylayer.com/tools/verimem/hippo-skills-derive-predicates-batch.md
- `hippo_world_simulate` — Execute — https://policylayer.com/tools/verimem/hippo-world-simulate.md
- `sandbox_exec` — Execute — https://policylayer.com/tools/verimem/sandbox-exec.md
- `hippo_dream_propose` — Other — https://policylayer.com/tools/verimem/hippo-dream-propose.md
- `hippo_agent_specialization` — Read — https://policylayer.com/tools/verimem/hippo-agent-specialization.md
- `hippo_agent_workload` — Read — https://policylayer.com/tools/verimem/hippo-agent-workload.md
- `hippo_anchor_recall` — Read — https://policylayer.com/tools/verimem/hippo-anchor-recall.md
- `hippo_anti_confab_scan` — Read — https://policylayer.com/tools/verimem/hippo-anti-confab-scan.md
- `hippo_assess_confidence` — Read — https://policylayer.com/tools/verimem/hippo-assess-confidence.md
- `hippo_assess_fact_freshness` — Read — https://policylayer.com/tools/verimem/hippo-assess-fact-freshness.md
- `hippo_audit_summary` — Read — https://policylayer.com/tools/verimem/hippo-audit-summary.md
- `hippo_audit_tail` — Read — https://policylayer.com/tools/verimem/hippo-audit-tail.md
- `hippo_briefing` — Read — https://policylayer.com/tools/verimem/hippo-briefing.md
- …and 206 more: https://policylayer.com/tools/verimem.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=verimem · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/verimem