validate_assumption
[SUPPORT] Confirm or invalidate the assumption a pinned decision rests on, in one call — no phase switching. Stamps the decision's assumption_status (confirmed|invalidated), saves a code-anchored note with your finding, and when confirmed=false fires a BLOCKING HITL so work depending on the decis...
This record as markdown: /tools/io-github-ajc3xc-meridian/validate-assumption.md
What validate_assumption does on Meridian
AI agents call validate_assumption to retrieve information from Meridian without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
symbol | string | — | Optional symbol within file_path. |
finding | string | Yes | What you found that confirms or refutes the assumption. |
confirmed | boolean | Yes | true = assumption holds; false = invalidated (fires a blocking HITL). |
file_path | string | — | Optional file path the finding is anchored to (code-anchored note). |
session_id | string | — | Session firing the validation; linked to the blocking HITL on invalidation. |
decision_id | string | Yes |
Parameters from the server's own tool schema.
Why validate_assumption is rated Low
Even though validate_assumption only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Risk signalsAccepts file system path (file_path)
Attacks that exploit this kind of access
The rule that runs validate_assumption safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Meridian, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For validate_assumption, this is the rule to start with:
validate_assumption is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Meridian, apply this rule, and every validate_assumption call is checked against it from then on.
Questions about validate_assumption
[SUPPORT] Confirm or invalidate the assumption a pinned decision rests on, in one call — no phase switching. Stamps the decision's assumption_status (confirmed|invalidated), saves a code-anchored note with your finding, and when confirmed=false fires a BLOCKING HITL so work depending on the decision pauses for human judgment. Use the moment you discover whether an assumption holds (a planning-session prospect moment). Persistent-state disclosure: on hosted Meridian, supplied text and project/session metadata -- including task log entries, pinned decisions, sprint items, notes, handoff/goal state, and HITL queue items -- are sent to and stored in Meridian's service, in an isolated per-tenant Postgres database (Neon); self-hosted deployments keep the same categories in the configured local SQLite/Postgres database. This data is visible in the dashboard and API, and may resurface in later project context or handoffs. Notes and pinned decisions can be deleted individually; task log entries and sprint items can be deleted via the dashboard/API (not exposed as an agent-facing tool); HITL queue items and handoff state have no per-record delete. Full removal of any of this data is available via project or account deletion, using the documented controls. Do not include secrets. It is categorised as a Read tool in the Meridian MCP Server, which means it retrieves data without modifying state.
validate_assumption accepts 6 parameters: symbol, finding, confirmed, file_path, session_id, decision_id. Required: finding, confirmed, decision_id. The full parameter table on this page comes from the server's own tool schema.
Register the Meridian MCP server in PolicyLayer and add a rule for validate_assumption: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Meridian. Nothing to install.
validate_assumption is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the validate_assumption rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for validate_assumption. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
validate_assumption is provided by the Meridian MCP server (@meridianmcp/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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