receive_messages
[MAINTENANCE] PARALLEL COORDINATION (d3a3a01d): fetch unread messages addressed to a session (oldest first) and mark them read by default. The receive side of send_message. Persistent-state disclosure: on hosted Meridian, supplied text and project/session metadata are sent to and stored in Meridi...
This record as markdown: /tools/io-github-ajc3xc-meridian/receive-messages.md
What receive_messages does on Meridian
AI agents call receive_messages 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 |
|---|---|---|---|
limit | integer | — | Max messages (default 50). |
mark_read | boolean | — | Mark fetched messages read (default true). |
session_id | string | Yes | The recipient session. |
Parameters from the server's own tool schema.
Why receive_messages is rated Low
The primary action is fetching/reading unread messages, which is a Read operation. Marking messages as read is a minor state change but not a meaningful Write in terms of blast radius. The medium severity reflects that messages may contain sensitive session/project metadata stored persistently in Meridian's service, and disclosure of that data to an unintended recipient could have moderate impact.
From the tool's definition fetch unread messages addressed to a session (oldest first) and mark them read by default. The receive side of send_message.
Attacks that exploit this kind of access
The rule that runs receive_messages 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 receive_messages, this is the rule to start with:
receive_messages 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 receive_messages call is checked against it from then on.
Questions about receive_messages
[MAINTENANCE] PARALLEL COORDINATION (d3a3a01d): fetch unread messages addressed to a session (oldest first) and mark them read by default. The receive side of send_message. Persistent-state disclosure: on hosted Meridian, supplied text and project/session metadata are sent to and stored in Meridian's service; self-hosted deployments keep them in the configured local SQLite/Postgres database. This data is visible in the dashboard/API and later project context or handoffs. Delete individual tasks, notes, or decisions where supported, or delete the project/account 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.
receive_messages accepts 3 parameters: limit, mark_read, session_id. Required: session_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 receive_messages: 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.
receive_messages 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 receive_messages 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 receive_messages. 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.
receive_messages 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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