set_agent_instructions

SERVERMeridian SOURCE@meridianmcp/mcp

Medium RISK CLASS

Category Write

Parameters 31 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-ajc3xc-meridian/set-agent-instructions.md

WHAT IT DOES

What set_agent_instructions does on Meridian

AI agents use set_agent_instructions to create or update resources in Meridian, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Meridian environment.

Parameter	Type	Required	Description
`project_id`	string	—
`instructions`	string	Yes	Markdown text injected at session start. Pass null to clear.
`project_name`	string	—	Project name — an alternative to project_id; resolved to the id internally. project_id wins if both are given.

Parameters from the server's own tool schema.

RISK

Why set_agent_instructions is rated Medium

This tool creates or modifies persistent configuration data (agent instructions) rather than deleting it irreversibly. While it affects system behavior by injecting instructions into sessions, the changes are reversible—instructions can be updated or cleared.

From the tool's definition Tool description states 'Set or update the custom agent_instructions' and 'Pass null or empty string to clear', indicating reversible creation and modification of data. The instructions are stored in a database (SQLite/Postgres) and can be updated or cleared.

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs set_agent_instructions 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 set_agent_instructions, this is the rule to start with:

set_agent_instructions Rate-limited

set_agent_instructions stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_agent_instructions": {
      "limits": [
        {
          "counter": "set_agent_instructions_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Meridian, apply this rule, and every set_agent_instructions call is checked against it from then on.

FAQ

Questions about set_agent_instructions

What does the set_agent_instructions tool do? +

[MAINTENANCE] Set or update the custom agent_instructions for a project. Instructions are injected into every start_session response so AI sessions see them automatically — no need to repeat in every session. Pass null or empty string to clear. Use for persistent rules like coding conventions, deploy steps, or codebase notes. 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 Write tool in the Meridian MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does set_agent_instructions accept? +

set_agent_instructions accepts 3 parameters: project_id, instructions, project_name. Required: instructions. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on set_agent_instructions? +

Register the Meridian MCP server in PolicyLayer and add a rule for set_agent_instructions: 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.

What risk level is set_agent_instructions? +

set_agent_instructions is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_agent_instructions? +

Yes. Add a rate_limit block to the set_agent_instructions 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.

How do I block set_agent_instructions completely? +

Set action: deny in the PolicyLayer policy for set_agent_instructions. 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.

What MCP server provides set_agent_instructions? +

set_agent_instructions 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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