Store a fact, decision, observation, or question worth remembering. Always add dimensions (person, project, topic, etc.) to make retrieval easier. Use this whenever notable information comes up that should be preserved for future reference.
AI agents use capture_thought to create or update resources in Brain — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Brain environment.
This tool creates new records in the semantic memory system (storing thoughts with vector embeddings and dimensional tags). It is reversible (thoughts can be archived or updated), causes no side effects beyond data creation, and poses minimal risk if an AI agent misuses it by storing irrelevant or false information—the impact is confined to polluting the user's own memory store, not external systems or destructive…
From the tool's definition Tool description explicitly states 'Store a fact, decision, observation, or question' and 'preserve for future reference', indicating creation and persistent modification of data in the PostgreSQL backend.
Attacks that exploit this kind of access
Store a fact, decision, observation, or question worth remembering. Always add dimensions (person, project, topic, etc.) to make retrieval easier. Use this whenever notable information comes up that should be preserved for future reference. It is categorised as a Write tool in the Brain MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Brain MCP server in PolicyLayer and add a rule for capture_thought: 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 Brain. Nothing to install.
capture_thought is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the capture_thought 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 capture_thought. 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.
capture_thought is provided by the Brain MCP server (markschaake/brain-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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